第 20042 題：Euler定理

原題與已知條件

n大於等於2、exact gcd、phi與安全modular exponentiation。操作=eulerthm-negative-base-normalization；資料={"n":21,"a":-19}。請依 exact_ordered_tuple_declared_by_interface 欄序回答。

• G001 — n大於等於2、exact gcd、phi與安全modular exponentiation。操作=eulerthm-negative-base-normalization；資料={"n":21,"a":-19}。請依 exact_ordered_tuple_declared_by_interface 欄序回答。

定義與適用範圍

沿用原題明示的論域、假設與來源 MKO 定義。本題已完成第二對話數理與中英語義覆核，並由原始參數逐題獨立重算模型、答案與每個算術步驟；原題仍為 candidate。

• mko-euler-theorem-number-theory

逐步推導

source operation=eulerthm-negative-base-normalization;original snapshot and mathematics retained

explicit ordered source output fields=[original_base, normalized_base, totient, residue, congruent_to_one, certificate]

Euler ORIGINAL signed base normalization exact quotient := div(-19, 21)

Euler ORIGINAL signed base normalization exact quotient = -19/21

Euler ORIGINAL signed base normalization floor quotient multiple := mul(-1, 21)

Euler ORIGINAL signed base normalization floor quotient multiple = -21

Euler ORIGINAL signed base normalization normalized remainder := sub(-19, -21)

Euler ORIGINAL signed base normalization normalized remainder = 2

Euler ORIGINAL signed base normalization:ORIGINAL signed integer=-19;modulus=21;exact ratio=-19/21;floor quotient=-1

value=q*n+remainder;normalized residue=2 in[0,21);same congruence class,NOT absolute-value replacement

Euler ORIGINAL base applicability gcd:ORIGINAL gcd inputs=[-19, 21];nonnegative initial pair=[19, 21]

ALL exact Euclidean rows[left,right,q,r]=[[19, 21, 0, 19], [21, 19, 1, 2], [19, 2, 9, 1], [2, 1, 2, 0]];terminal gcd=1

Euler residue representative0:ORIGINAL gcd inputs=[0, 21];nonnegative initial pair=[0, 21]

ALL exact Euclidean rows[left,right,q,r]=[[0, 21, 0, 0]];terminal gcd=21

Euler residue representative1:ORIGINAL gcd inputs=[1, 21];nonnegative initial pair=[1, 21]

ALL exact Euclidean rows[left,right,q,r]=[[1, 21, 0, 1], [21, 1, 21, 0]];terminal gcd=1

Euler residue representative2:ORIGINAL gcd inputs=[2, 21];nonnegative initial pair=[2, 21]

ALL exact Euclidean rows[left,right,q,r]=[[2, 21, 0, 2], [21, 2, 10, 1], [2, 1, 2, 0]];terminal gcd=1

Euler residue representative3:ORIGINAL gcd inputs=[3, 21];nonnegative initial pair=[3, 21]

ALL exact Euclidean rows[left,right,q,r]=[[3, 21, 0, 3], [21, 3, 7, 0]];terminal gcd=3

Euler residue representative4:ORIGINAL gcd inputs=[4, 21];nonnegative initial pair=[4, 21]

ALL exact Euclidean rows[left,right,q,r]=[[4, 21, 0, 4], [21, 4, 5, 1], [4, 1, 4, 0]];terminal gcd=1

Euler residue representative5:ORIGINAL gcd inputs=[5, 21];nonnegative initial pair=[5, 21]

ALL exact Euclidean rows[left,right,q,r]=[[5, 21, 0, 5], [21, 5, 4, 1], [5, 1, 5, 0]];terminal gcd=1

Euler residue representative6:ORIGINAL gcd inputs=[6, 21];nonnegative initial pair=[6, 21]

ALL exact Euclidean rows[left,right,q,r]=[[6, 21, 0, 6], [21, 6, 3, 3], [6, 3, 2, 0]];terminal gcd=3

Euler residue representative7:ORIGINAL gcd inputs=[7, 21];nonnegative initial pair=[7, 21]

ALL exact Euclidean rows[left,right,q,r]=[[7, 21, 0, 7], [21, 7, 3, 0]];terminal gcd=7

Euler residue representative8:ORIGINAL gcd inputs=[8, 21];nonnegative initial pair=[8, 21]

ALL exact Euclidean rows[left,right,q,r]=[[8, 21, 0, 8], [21, 8, 2, 5], [8, 5, 1, 3], [5, 3, 1, 2], [3, 2, 1, 1], [2, 1, 2, 0]];terminal gcd=1

Euler residue representative9:ORIGINAL gcd inputs=[9, 21];nonnegative initial pair=[9, 21]

ALL exact Euclidean rows[left,right,q,r]=[[9, 21, 0, 9], [21, 9, 2, 3], [9, 3, 3, 0]];terminal gcd=3

Euler residue representative10:ORIGINAL gcd inputs=[10, 21];nonnegative initial pair=[10, 21]

ALL exact Euclidean rows[left,right,q,r]=[[10, 21, 0, 10], [21, 10, 2, 1], [10, 1, 10, 0]];terminal gcd=1

Euler residue representative11:ORIGINAL gcd inputs=[11, 21];nonnegative initial pair=[11, 21]

ALL exact Euclidean rows[left,right,q,r]=[[11, 21, 0, 11], [21, 11, 1, 10], [11, 10, 1, 1], [10, 1, 10, 0]];terminal gcd=1

Euler residue representative12:ORIGINAL gcd inputs=[12, 21];nonnegative initial pair=[12, 21]

ALL exact Euclidean rows[left,right,q,r]=[[12, 21, 0, 12], [21, 12, 1, 9], [12, 9, 1, 3], [9, 3, 3, 0]];terminal gcd=3

Euler residue representative13:ORIGINAL gcd inputs=[13, 21];nonnegative initial pair=[13, 21]

ALL exact Euclidean rows[left,right,q,r]=[[13, 21, 0, 13], [21, 13, 1, 8], [13, 8, 1, 5], [8, 5, 1, 3], [5, 3, 1, 2], [3, 2, 1, 1], [2, 1, 2, 0]];terminal gcd=1

Euler residue representative14:ORIGINAL gcd inputs=[14, 21];nonnegative initial pair=[14, 21]

ALL exact Euclidean rows[left,right,q,r]=[[14, 21, 0, 14], [21, 14, 1, 7], [14, 7, 2, 0]];terminal gcd=7

Euler residue representative15:ORIGINAL gcd inputs=[15, 21];nonnegative initial pair=[15, 21]

ALL exact Euclidean rows[left,right,q,r]=[[15, 21, 0, 15], [21, 15, 1, 6], [15, 6, 2, 3], [6, 3, 2, 0]];terminal gcd=3

Euler residue representative16:ORIGINAL gcd inputs=[16, 21];nonnegative initial pair=[16, 21]

ALL exact Euclidean rows[left,right,q,r]=[[16, 21, 0, 16], [21, 16, 1, 5], [16, 5, 3, 1], [5, 1, 5, 0]];terminal gcd=1

Euler residue representative17:ORIGINAL gcd inputs=[17, 21];nonnegative initial pair=[17, 21]

ALL exact Euclidean rows[left,right,q,r]=[[17, 21, 0, 17], [21, 17, 1, 4], [17, 4, 4, 1], [4, 1, 4, 0]];terminal gcd=1

Euler residue representative18:ORIGINAL gcd inputs=[18, 21];nonnegative initial pair=[18, 21]

ALL exact Euclidean rows[left,right,q,r]=[[18, 21, 0, 18], [21, 18, 1, 3], [18, 3, 6, 0]];terminal gcd=3

Euler residue representative19:ORIGINAL gcd inputs=[19, 21];nonnegative initial pair=[19, 21]

ALL exact Euclidean rows[left,right,q,r]=[[19, 21, 0, 19], [21, 19, 1, 2], [19, 2, 9, 1], [2, 1, 2, 0]];terminal gcd=1

Euler residue representative20:ORIGINAL gcd inputs=[20, 21];nonnegative initial pair=[20, 21]

ALL exact Euclidean rows[left,right,q,r]=[[20, 21, 0, 20], [21, 20, 1, 1], [20, 1, 20, 0]];terminal gcd=1

Euler complete reduced residue count phi := sum(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)

Euler complete reduced residue count phi = 12

COMPLETE original residue carrier0..20;ALL [representative,gcd,unit] rows=[[0, 21, 否], [1, 1, 是], [2, 1, 是], [3, 3, 否], [4, 1, 是], [5, 1, 是], [6, 3, 否], [7, 7, 否], [8, 1, 是], [9, 3, 否], [10, 1, 是], [11, 1, 是], [12, 3, 否], [13, 1, 是], [14, 7, 否], [15, 3, 否], [16, 1, 是], [17, 1, 是], [18, 3, 否], [19, 1, 是], [20, 1, 是]]

increasing COMPLETE U(n)=[1, 2, 4, 5, 8, 10, 11, 13, 16, 17, 19, 20];phi(n)=12;source count over1..n agrees because0 and n are BOTH nonunits for n>=2

ORIGINAL normalized base=2;COMPLETE totient exponent=12;modulus=21

initialize accumulator1,current_base=base,remaining=phi;invariant accumulator*current_base^remaining congruent to the original totient power

Euler power bit0 base square := mul(2, 2)

Euler power bit0 base square = 4

Euler power bit0 squared-base reduction exact quotient := div(4, 21)

Euler power bit0 squared-base reduction exact quotient = 4/21

Euler power bit0 squared-base reduction floor quotient multiple := mul(0, 21)

Euler power bit0 squared-base reduction floor quotient multiple = 0

Euler power bit0 squared-base reduction normalized remainder := sub(4, 0)

Euler power bit0 squared-base reduction normalized remainder = 4

Euler power bit0 squared-base reduction:ORIGINAL signed integer=4;modulus=21;exact ratio=4/21;floor quotient=0

value=q*n+remainder;normalized residue=4 in[0,21);same congruence class,NOT absolute-value replacement

step=0;previous[accumulator,base,exponent]=[1, 2, 12];low bit=0

next[accumulator,base,exponent]=[1, 4, 6];split exponent=2*q+bit preserves original-power invariant

Euler power bit1 base square := mul(4, 4)

Euler power bit1 base square = 16

Euler power bit1 squared-base reduction exact quotient := div(16, 21)

Euler power bit1 squared-base reduction exact quotient = 16/21

Euler power bit1 squared-base reduction floor quotient multiple := mul(0, 21)

Euler power bit1 squared-base reduction floor quotient multiple = 0

Euler power bit1 squared-base reduction normalized remainder := sub(16, 0)

Euler power bit1 squared-base reduction normalized remainder = 16

Euler power bit1 squared-base reduction:ORIGINAL signed integer=16;modulus=21;exact ratio=16/21;floor quotient=0

value=q*n+remainder;normalized residue=16 in[0,21);same congruence class,NOT absolute-value replacement

step=1;previous[accumulator,base,exponent]=[1, 4, 6];low bit=0

next[accumulator,base,exponent]=[1, 16, 3];split exponent=2*q+bit preserves original-power invariant

Euler power bit2 accumulator product := mul(1, 16)

Euler power bit2 accumulator product = 16

Euler power bit2 accumulator reduction exact quotient := div(16, 21)

Euler power bit2 accumulator reduction exact quotient = 16/21

Euler power bit2 accumulator reduction floor quotient multiple := mul(0, 21)

Euler power bit2 accumulator reduction floor quotient multiple = 0

Euler power bit2 accumulator reduction normalized remainder := sub(16, 0)

Euler power bit2 accumulator reduction normalized remainder = 16

Euler power bit2 accumulator reduction:ORIGINAL signed integer=16;modulus=21;exact ratio=16/21;floor quotient=0

value=q*n+remainder;normalized residue=16 in[0,21);same congruence class,NOT absolute-value replacement

Euler power bit2 base square := mul(16, 16)

Euler power bit2 base square = 256

Euler power bit2 squared-base reduction exact quotient := div(256, 21)

Euler power bit2 squared-base reduction exact quotient = 256/21

Euler power bit2 squared-base reduction floor quotient multiple := mul(12, 21)

Euler power bit2 squared-base reduction floor quotient multiple = 252

Euler power bit2 squared-base reduction normalized remainder := sub(256, 252)

Euler power bit2 squared-base reduction normalized remainder = 4

Euler power bit2 squared-base reduction:ORIGINAL signed integer=256;modulus=21;exact ratio=256/21;floor quotient=12

value=q*n+remainder;normalized residue=4 in[0,21);same congruence class,NOT absolute-value replacement

step=2;previous[accumulator,base,exponent]=[1, 16, 3];low bit=1

next[accumulator,base,exponent]=[16, 4, 1];split exponent=2*q+bit preserves original-power invariant

Euler power bit3 accumulator product := mul(16, 4)

Euler power bit3 accumulator product = 64

Euler power bit3 accumulator reduction exact quotient := div(64, 21)

Euler power bit3 accumulator reduction exact quotient = 64/21

Euler power bit3 accumulator reduction floor quotient multiple := mul(3, 21)

Euler power bit3 accumulator reduction floor quotient multiple = 63

Euler power bit3 accumulator reduction normalized remainder := sub(64, 63)

Euler power bit3 accumulator reduction normalized remainder = 1

Euler power bit3 accumulator reduction:ORIGINAL signed integer=64;modulus=21;exact ratio=64/21;floor quotient=3

value=q*n+remainder;normalized residue=1 in[0,21);same congruence class,NOT absolute-value replacement

Euler power bit3 base square := mul(4, 4)

Euler power bit3 base square = 16

Euler power bit3 squared-base reduction exact quotient := div(16, 21)

Euler power bit3 squared-base reduction exact quotient = 16/21

Euler power bit3 squared-base reduction floor quotient multiple := mul(0, 21)

Euler power bit3 squared-base reduction floor quotient multiple = 0

Euler power bit3 squared-base reduction normalized remainder := sub(16, 0)

Euler power bit3 squared-base reduction normalized remainder = 16

Euler power bit3 squared-base reduction:ORIGINAL signed integer=16;modulus=21;exact ratio=16/21;floor quotient=0

value=q*n+remainder;normalized residue=16 in[0,21);same congruence class,NOT absolute-value replacement

step=3;previous[accumulator,base,exponent]=[16, 4, 1];low bit=1

next[accumulator,base,exponent]=[1, 16, 0];split exponent=2*q+bit preserves original-power invariant

remaining exponent0;final normalized accumulator=1

EXACT original normalized base^12 modulo21=1

Euler ACTUAL base-unit inverse product := mul(2, 11)

Euler ACTUAL base-unit inverse product = 22

Euler ACTUAL inverse check exact quotient := div(22, 21)

Euler ACTUAL inverse check exact quotient = 22/21

Euler ACTUAL inverse check floor quotient multiple := mul(1, 21)

Euler ACTUAL inverse check floor quotient multiple = 21

Euler ACTUAL inverse check normalized remainder := sub(22, 21)

Euler ACTUAL inverse check normalized remainder = 1

Euler ACTUAL inverse check:ORIGINAL signed integer=22;modulus=21;exact ratio=22/21;floor quotient=1

value=q*n+remainder;normalized residue=1 in[0,21);same congruence class,NOT absolute-value replacement

ACTUAL modulus n=21;gcd(original a=-19,n)=1;normalized base=2;ACTUAL inverse=11;COMPLETE U(n)=[1, 2, 4, 5, 8, 10, 11, 13, 16, 17, 19, 20]

for ANY r in U(n),a*r remains a unit;actual inverse makes multiplication injective;finite self-injection on U(n) is surjective,so a*U(n)=U(n)

SAME complete U(n)=[1, 2, 4, 5, 8, 10, 11, 13, 16, 17, 19, 20] of size phi=12;multiplication by original a=-19 permutes it

multiply ALL unit images:a^(12)*product(U) congruent product(U);EVERY U factor is a UNIT,so product(U) has reverse-product inverse;cancel ONLY this unit to get a^phi congruent1 modulo21

逐步反向核對

• S072 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S071 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S070 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S069 · premise_and_result_audit — 以精確有理數重算 Euler ACTUAL inverse check normalized remainder，不以小數近似替代。
• S068 · premise_and_result_audit — 以精確有理數重算 Euler ACTUAL inverse check floor quotient multiple，不以小數近似替代。
• S067 · premise_and_result_audit — 以精確有理數重算 Euler ACTUAL inverse check exact quotient，不以小數近似替代。
• S066 · premise_and_result_audit — 以精確有理數重算 Euler ACTUAL base-unit inverse product，不以小數近似替代。
• S065 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S064 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S063 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S062 · premise_and_result_audit — 以精確有理數重算 Euler power bit3 squared-base reduction normalized remainder，不以小數近似替代。
• S061 · premise_and_result_audit — 以精確有理數重算 Euler power bit3 squared-base reduction floor quotient multiple，不以小數近似替代。
• S060 · premise_and_result_audit — 以精確有理數重算 Euler power bit3 squared-base reduction exact quotient，不以小數近似替代。
• S059 · premise_and_result_audit — 以精確有理數重算 Euler power bit3 base square，不以小數近似替代。
• S058 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S057 · premise_and_result_audit — 以精確有理數重算 Euler power bit3 accumulator reduction normalized remainder，不以小數近似替代。
• S056 · premise_and_result_audit — 以精確有理數重算 Euler power bit3 accumulator reduction floor quotient multiple，不以小數近似替代。
• S055 · premise_and_result_audit — 以精確有理數重算 Euler power bit3 accumulator reduction exact quotient，不以小數近似替代。
• S054 · premise_and_result_audit — 以精確有理數重算 Euler power bit3 accumulator product，不以小數近似替代。
• S053 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S052 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S051 · premise_and_result_audit — 以精確有理數重算 Euler power bit2 squared-base reduction normalized remainder，不以小數近似替代。
• S050 · premise_and_result_audit — 以精確有理數重算 Euler power bit2 squared-base reduction floor quotient multiple，不以小數近似替代。
• S049 · premise_and_result_audit — 以精確有理數重算 Euler power bit2 squared-base reduction exact quotient，不以小數近似替代。
• S048 · premise_and_result_audit — 以精確有理數重算 Euler power bit2 base square，不以小數近似替代。
• S047 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S046 · premise_and_result_audit — 以精確有理數重算 Euler power bit2 accumulator reduction normalized remainder，不以小數近似替代。
• S045 · premise_and_result_audit — 以精確有理數重算 Euler power bit2 accumulator reduction floor quotient multiple，不以小數近似替代。
• S044 · premise_and_result_audit — 以精確有理數重算 Euler power bit2 accumulator reduction exact quotient，不以小數近似替代。
• S043 · premise_and_result_audit — 以精確有理數重算 Euler power bit2 accumulator product，不以小數近似替代。
• S042 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S041 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S040 · premise_and_result_audit — 以精確有理數重算 Euler power bit1 squared-base reduction normalized remainder，不以小數近似替代。
• S039 · premise_and_result_audit — 以精確有理數重算 Euler power bit1 squared-base reduction floor quotient multiple，不以小數近似替代。
• S038 · premise_and_result_audit — 以精確有理數重算 Euler power bit1 squared-base reduction exact quotient，不以小數近似替代。
• S037 · premise_and_result_audit — 以精確有理數重算 Euler power bit1 base square，不以小數近似替代。
• S036 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S035 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S034 · premise_and_result_audit — 以精確有理數重算 Euler power bit0 squared-base reduction normalized remainder，不以小數近似替代。
• S033 · premise_and_result_audit — 以精確有理數重算 Euler power bit0 squared-base reduction floor quotient multiple，不以小數近似替代。
• S032 · premise_and_result_audit — 以精確有理數重算 Euler power bit0 squared-base reduction exact quotient，不以小數近似替代。
• S031 · premise_and_result_audit — 以精確有理數重算 Euler power bit0 base square，不以小數近似替代。
• S030 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S029 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S028 · premise_and_result_audit — 以精確有理數重算 Euler complete reduced residue count phi，不以小數近似替代。
• S027 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S026 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S025 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S024 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S023 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S022 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S021 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S020 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S019 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S018 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S017 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S016 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S015 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S014 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S013 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S012 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S011 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S010 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S009 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S008 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S007 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S006 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S005 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。
• S004 · premise_and_result_audit — 以精確有理數重算 Euler ORIGINAL signed base normalization normalized remainder，不以小數近似替代。
• S003 · premise_and_result_audit — 以精確有理數重算 Euler ORIGINAL signed base normalization floor quotient multiple，不以小數近似替代。
• S002 · premise_and_result_audit — 以精確有理數重算 Euler ORIGINAL signed base normalization exact quotient，不以小數近似替代。
• S001 · premise_and_result_audit — 回到原始資料與本步條件核對，不把單向推論誤稱等價。

結論

(-19, 2, 12, 1, 是, negative_base_normalized_before_exact_modular_power)

依上列完整代值及條件核對得到原題答案；原題編號、格式與狀態保持不變。

本題覆核與來源綁定

覆核日期：2026-10-26

原題、答案、步驟表達式、數值 AST 與既有歷史保持原樣；原來的候選狀態屬於來源歷史，不覆寫為形式化證明。