Optimism had been growing ________ the weekend meeting of European Union leaders in Brussels

would come up with a substantial plan for dealing with the debt crisis.  [ ]

A. when

B. before

C. what

D. that

接种乙肝疫苗前是否需要进行乙肝血清学筛检？（）

A、必须做筛检后才能接种乙肝疫苗

B、成人必须做筛检后才能接种乙肝疫苗

C、接种乙肝疫苗前可以不做血清学筛检

D、未进行筛检就接种乙肝疫苗时非常危险的