设A是三角形矩阵,那么A可逆的充分必要条件是A的主对角线元素为().
A. 全都非负
B. 不全为0
C. 全不为0
D. 没有限制
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-- Have you met her before? -- ___________. -- But she knows what you look like.
A. Sure
B. Yes, I did
C. Not yet
D. None of your business
He noticed a _____ note on the ground and picked it up.
A. one-hundred-dollar
B. one hundreds dollars
C. one hundreds dollar
D. one hundred dollars
-- ________is the restaurant from the post office?-- It's about 5 minutes' ride.
A. How long
B. How often
C. How far
D. How many
The number of students in this school ______ by 5% every year.
A. rise
B. raise
C. rises
D. raises