蛋白质分子一定具有（）

A.α-螺旋

B.β-折叠

C.三级结构

D.四级结构

E.亚基

句型转换。

1. Our zoo has about three thousand animals. (对画线部分提问)

    ______________________________?

2. The animals are behind the wall. (对画线部分提问)

    ______________________________?

3. The giraffe doesn't eat meat. (改为肯定句)

    ______________________________.

4. My friend Bob lives in Europe. (对画线部分提问)

    ______________________________?

5. Does the elephant like water? (作肯定回答)

    ______________________________.