Shirley _____ a book about China last year, but I don't know whether she has finished it.

A．has written

B．wrote

C．had written

D．was writing

外用攻毒杀虫，蚀疮去腐，内服劫痰平喘，截疟的药物是

A．硼砂

B．砒石

C．硫黄

D．白矾