（20+25）÷35
=45÷35
=75（页）；
答：这本科技书有75页．
— Are you free after school?
— Sorry. I've planned to treat a friend of mine to dinner________for his help. [ ]
A. in addition
B. in turn
C. in return
D. in total
药物从给药部位进入体循环的过程称为（）
A.AUC
B.吸收
C.分布
D.代谢
E.排泄
