向量组(I)与向量组(II)可以互相线性表出是向量组(I)与向量组（II）等价的___________条件;向量组(I)与向量组(II)的秩相等是向量组(I)与向量组（II）等价的___________条件。（填充要；必要；充分）
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Q: When did the man first do a triathlon?
A. Last year.
B. In college.
C. Last week.
D. In high school.
How does the man feel about running?
A. Boring.
B. Scaring.
C. Exciting.
D. Interesting.
Why doesn’t the woman like swimming in the triathlon?
A. Because she fears that a big fish might eat her.
Because she fears that she would get lost in lakes.
C. Because she doesn’t want to scare away small fishes.
D. Because she doesn’t like swimming with many people.
Q: What is the most exciting finding about increasingpositive emotions?
A. It improves relationships.
B. It leads to greater success.
C. It helps develop creativity.
D. It contributes to good health.
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