【C5】A．whyB．whichC．becauseD．what

The reason why Jack failed to attend the lecture is because he had a had cold.A．whyB．faile

【C5】A．whenB．whichC．howD．it

It is because English is very useful ________we study it hard.A: whyB: thatC: whatD: w

I doubt_____he is the murderer because he is not on the scene at that moment.A．whyB．thatC．

【C8】A．thatB．whichC．becauseD．as

【C5】A．howB．whichC．thatD．what