My brother ___ in his school for two years. [ ]
A. were
B. has been
C. is
D. is being
答案:B
有机磷农药中毒的解救药物是
A.毛果芸香碱B.药用炭C.乙酰胆碱D.阿托品E.新斯的明
何谓围生期国际上对围生期有几种规定我国现阶段采用哪一种