句型转换。

1. Bob gets to school by train. (对画线部分提问)

   _______ does Bob get to school?

2. Wang Jie is 14 years old. Wang Lei is 14 years, too. (合成一句话)

   Wang Jie is ________ ________ ________ Wang Lei.

3. Sarah is a student. Marie is a student, too. (合成一句话)

    ________ Sarah ________ Marie ________ students.

4. This box is heavy. That box is light. (合成一句话)

   This box is _______ ________ that one.

5. We need two teaspoons of sugar. (对画线部分提问)

   How _______ teaspoons of sugar do you need?

成人骨大约由1/3的有机质和2/3的无机质构成，有机质的主要成分是骨胶原，约占90%，无机质的主要组成部分是（）。

A.骨基质

B.骨胶纤维

C.骨细胞

D.钙盐

E.骨胶原