单选题：______ all of them are strong candidates, only one will be c..

—I called you at 9 last night，but no one answered.—Sorry，I ________ sleeping.I went to bed very early. A．need have beenB．would have beenC．must have beenD．should have been

All of them turned a deaf ear to his suggestion, _____ they knew it to be valuable.A. as if B. now that C. even though D. so that

She understood what I was talking about, _____ it was the first time we had spoken together.A. whether B. even though C. as though D. since

(2013·合肥第二次质检)Martin hasn't been in touch with me for ages. He ________ my new cellphone number.A．needn't get B．mustn't getC．can't get D．shouldn't have got

The haze or smog was so serious that the winter running _________.Some students complained as they ranA．could have cancelledB．should have cancelledC．must have been cancelledD．ought to have been cancelled