牙拔除后3～4天，出现拔牙创剧烈疼痛，最可能是（）。

A.干槽症

B.牙槽突骨折

C.牙龈损伤

D.牙槽窝内有异物

E.过高骨嵴和骨尖

句型转换。

1. My father stayed there for two months. (对划线部分提问)

    ________ ________ did your father ______ there?

2. He went to school at the age of seven. (改为同义句)

    He went to school ________ he ________ seven years ________.

3. This bike is new. (改为复数句子)

     ________ bikes ________ new.

4. We played basketball yesterday afternoon. (对划线部分提问)

    ________ ________ you ________ yesterday afternoon?

5. He is too short. He can't reach the banana. (改为一句话)

    He is ________ short ________ ________ the banana.