头孢菌素类抗生素保持生物活性的基本结构是A.6-氨基青霉烷酸（6-APA)B.7-氨基头孢烷酸（7

(A)Is it too far to walk？

(B) You’re welcome.

(C) Sure. Go down the street and you’ll see it at the first traffic lights.

(D) Pardon？ I have no idea.

听力原文：Where did you get your first pay？

(A) From a company that I only stayed for half a year.

(B) Yes, I paid for it.

(C) I get my pay each Friday.

(16)

A．

B．

C．

A．正确

B．错误

– I got the first prize! --____________

A、I got a prize too.

B、Well done!

C、When did you get it？

D、Come on!

B.these things

C.that things

D.those thing

B.does

C.to do

D.doing