【C7】A．WhenB．LestC．UnlessD．If

【C19】A．whenB．whereC．howD．if

【C7】A．whenB．whereC．howD．what

【C13】A．whenB．whatC．thatD．if

【C7】A．whenB．whichC．whereD．that

Doctors won t operate on the patient______absolutely necessary.A．whenB．ifC．unlessD．though

【C7】A．whenB．whereC．whomD．that