完成对话。

A: Hello !小题1:

B: Yes . What’s up ?

A:小题2:Could I borrow your bike again ?

B: Certainly .小题3:Has your bike been broken again ?

A: No . I’ve lost my key to the bike . But I have to go to see a friend .

B: I see .小题4:

A: About four o’clock .

B: OK . Here is the key .

A:小题5:

B: Bye !

抗癌药物对骨髓的抑制作用与血细胞半寿期有关，红细胞的半寿期为（）

A.120d

B.100d

C.80d

D.60d

E.40d