题目内容

TextChristmas was a (8) affair when I grew up. There were just my parents and I. I vowed (9) someday I’ d marry and have six children, and at Christmas my house would (10) with energy and love.I found the man (11) shared my dream, but we had not reckoned (12) the possibility of (13) . Undaunted, we applied (14) adoption, and then he arrived.We called him Our Christmas Boy (15) he came to us during that season of joy. Then nature surprised us again. We (16) two biological children to the family—not as many as we had (17) for, but three made an entirely satisfactory (18) .As Our Christmas Boy grew, he made it clear that only he had the expertise to select and (19) the Christmas tree. He rushed the season, starting his gift list in November. He pressed us into singing carols, our froglike voices contrasting (20) his (21) gift of perfect pitch. Each holiday he (22) us up, leading us through a round of merry chaos.Then, on his 26th Christmas, he left us in a car accident (23) his way home to his wife and infant daughter. But first he had stopped (24) the family home to decorate our tree.(25) -stricken, his father and I sold our home, where memories (26) every room, and moved away. Seventeen years later, we grew old enough to return home, and (27) into a small quiet house, like the house of my childhood. Our other son and daughter had married and had begun their own Christmas traditions in another part of the country.… 18().

A. harmony
B. order
C. balance
D. crowd

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设n维向量组α1,α2,…,αs的秩等于3,则______。

A. α1,α2,…,αs中的任何4个向量相关,任何3个向量无关
B. 存在含有两个向量的无关的部分组
C. 相关的部分组包含向量的个数多于3
D. 如果S>3,则α1,α2,…,αs中有零向量

设A是4×5矩阵,α1,α2,α3,α4,α5是A的列向量组,r(A)=3,则______正确。

A的任何3个行向量都线性无关
B. A的任何阶数大于3的子式都是0子式,任何3阶子式都为非0子式
C. α1,α2,α3,α4,α5的含有3个向量的线性无关部分组一定是它的极大无关组
D. α1,α2,α3,α4,α5的线性相关的部分组一定含有多于3个向量

已知两个n维向量组α1,…,αm和β1,…,βm,若存在两组不全为零的数λ1,…,λm和k1,…,km,使(λ1+k1)α1+…+(λm+km)αm+(λ1-k1)β1+…+(λm-km)βm=0,则下列正确的是______。

A. α1,…,αm和β1,…,βm都线性无关
B. α1,…,αm和β1,…,βm都线性相关
C. α1+β1,…,αm+βm,α1-β1,…,αm-βm都线性相关
D. α1+β1,…,αm+βm,α1-β1,…,αm-βm都线性无关

向量组(Ⅰ):α1,…αm(m≥3)线性无关的充分必要条件是______。

A. 任意一个向量都不能由其余m-1个向量线性表出
B. 存在一个向量,它不能由其余m-1个向量线性表出
C. 任意两个向量线性无关
D. 存在不全为零的常数k1,…,km,使k1a1+…+kmam≠0,使k1a1+…+kmam≠0

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