【C5】A．BecauseB．WhenC．IfD．Whether

【B15】______A．thatB．whenC．ifD．because

A．BecauseB．WhenC．WhetherD．If

A．WhetherB．WhenC．IfD．Although

___________ 查看材料A.howB.whenC.whyD.whether

【C16】A．BecauseB．WhenC．BeforeD．Although

【C5】A．whichB．whereC．whenD．whether