– Have they found out the of the fire?
-- Yes. It was a cigarette end that the fire.
A. cause; started
B. reason; caused
C. causing; caused
D. reason; cause
网友回答
(答案→)A. cause; started
B. reason; caused
C. causing; caused
D. reason; cause
解析：第一空考查cause和reason的区别，cause是起因，和of搭配，reason是理由和for搭配，第二空考查start的起火，句意是：--你发现大火的起因吗？--是，是香烟头引起的大火。选A。