The traffic accident might have been caused by（).

The traffic accident()three days ago.

A. happens

B. took place

C. was occurred

Thirty-three people were already dead in a traffic accident and twelve of them being old men. ()

On June 1, 2000, he lost both legs in a serious traffic accident, which changed everything all of a sudden. Everything changed __________on June 1, 2000 when he lost both legs in a serious traffic accident. （）

A.prevented from

B.relieved of

C.held up

D.covered with

A.that

B.when

C.why

D.because

A.could avoid

B.would avoid

C.would have avoided

D.must have avoided