多黏菌素（）
A.抑制细胞壁的合成
B.影响细胞膜的通透性
C.抑制菌体蛋白质的合成
D.抑制细菌核酸合成
E.寄生于细菌体内
参考答案：B
—Excuse me, _____ can I get to the nearest bookshop?
—Go along this road and you will find it on your right. [ ]
A. why
B. where
C. when
D. how
— Sorry, Professor Smith. I didn't finish the assignment yesterday.
— Oh, you _____ have done it as yesterday was the deadline. [ ]
A. must
B. mustn't
C. should
D. shouldn't
