Many accidents by careless drivers last year.
A. are caused
B. were caused
C. have caused
D. will cause
网友回答
A. are caused
(答案→)B. were caused
C. have caused
D. will cause
解析：考查被动语态。句意：去年，许多事故是由粗心造成的。事故是被引起的，应该使用被动语态，再根据last year确定使用一般过去时，排除A、C、D。故选B。