【C15】A．howB．whatC．whyD．which

（)they are doing has never been done before.A. ThatB. WhatC. WhyD. Whether

A．whenB．whatC．whyD．how

【C16】A．thatB．whatC．whyD．how

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

【C5】A．howB．whereC．whyD．which

【C15】A．thatB．whatC．in thatD．in which