1.John opened the door__B____his father came in.(表示动作突然发生)
A.after B.when C.until D.while
2.__C____I was on my way home,I had a fall.（As作用=When）
A.until B.since C.as D.though
3.__D____the boy is not clever,I still believe he can do it well.（though表虽然）
A.because B.if C.when D.though
4.The bell will be ring__C____there is a fire.（什么破题目,应该是the bell is to ring,比will be ringing好）
A.even B.that C.if D.although
5.I don’t believe him,___C___he says.(say 及物动词,后面必须跟宾语)
A.however B.whenever C.whatever D.whereve