问题 单项选择题

下列哪项是错畸形的病因()。

A.牙列缺失

B.楔状缺损

C.四环素牙

D.氟斑牙

E.遗传因素

答案

参考答案:E

补全对话,情景问答

完成对话。

A: (1)                                                                                                                           ?

B: Go down this street, take the third crossing on the left, Then go straight ahead. Go past the supermarkt. 

    Walk about three blocks. You will see the post office is between the bank of China and the bookstore.

A: (2)                                                                                                                           ?

B: It's about fifeen minuts' walk. It's late now. you'd better take a bus.

A: (3)                                                                                                                            ?

B: No. 49 bus.

A: (4)                                                                                                                            ?

B: It will take you about five minutes to get there.

A: Thanks a lot.

B: (5)                                                                                                                             .

不定项选择