牛奶营养丰富，但许多人却无福享用，喝了反而会腹泻、胀气，这是为什么呢？德国科学家发现这是由于有些人体内缺少足够的能分解牛奶中乳糖的乳糖酶所致。下列关于酶的说法不正确的是 [ ]

A．蚕丝、绝大多数酶的主要成分都是蛋白质

B．在强酸或强碱存在下酶的催化活性最强

C．高温或重金属盐会使酶的催化活性降低

D．酶在一定条件下水解的最终产物是氨基酸

完成下面的对话，每空一词。

A: Hello! May I 1._____ to Toby?

B: Speaking!

A: Hi, Toby! 2. _____ is Tina speaking.

B: What's wrong?

A: I 3._____ you yesterday, but you were not at home. Where did you go?

B: I went to the aquarium(水族馆) 4._____ my parents.

A: Really? 5.____ was your trip?

B: It was great,. We saw the dolphins show. They're very wonderful.

A: That sounds 6._____.

B: By 7._____ way, why 8._____ you call me?

A: Oh, tomorrow is my . Would you come to my 9. _____ birthday party?

B: Yes, I'd 10. _____ to. Thanks a lot.