句型转换。

1. This is my father. (改为一般疑问句)

    _____ this _____ father?

2. My basketballs are in the box. (改为否定句)

    My basketballs _____ _____ in the box.

3. Mary's pencil is yellow. (对画线部分提问)

    _____ _____ is Mary's pencil?

4. I have a big sports collection.(改为一般疑问句) 

    _____ you _____ a big sports collection?

5. This is a ruler. (改为复数句)

    _____ are _____ .

硬膜外穿刺产生负压的主要原因()

A．硬膜外间隙原为负压

B．硬脊膜突然顶开

C．黄韧带突然顶开

D．穿刺针进入静脉

E．穿刺针进入蛛网膜下间隙