Charles Smith, ______ was my former teacher, retired last year.
B
that不能引导非限制性定语从句,可以用which和who引导,其中,who代替的先行词是人。句意为：查理?史密斯去年退休了,他曾经是我的老师。
Whenyou're_____acrisis,itoftenhelpstotalktosomeone.
Theprofessoraskedaquestion,andDavid________agoodanswer.
Aftermonthsofvoyage,Columbusarrivedin______laterprovedtobeanewcontinent.