do you know how the traffic accident was happened?这句话对么

do you know how the traffic accident was happened?这句话对么 do you know what（ ）（ cause）the traffic accident Where was ___ the traffic accident happened last night? Do you know anything about the accident happened in the stre -Do you know about the accident which happened in the center Do you know anything about the accident which happened in th Was it in front of the office()the traffic accident happened I don't know how the accident happened.当I don't know how the -What would you do if you _____ the traffic accident? It was said that an accident had happened and the traffic __ the traffic accident happened on the Guangshen Expressway.(用 The police are __ the traffic accident that happened yesterd