He could not help but ____ at the joke.A: laughB: to laughC: laughingD: laughed

Jack_____out very early, for he had not shown up at breakfast.A．could have goneB．must have

He ______ unwisely, but he was at least trying to do something helpful[1999]A．may have act

He kept asking questions, but not a word_____.A．could we understandB．we could understandC．

But that he saw it, he ___it.A、could not have believedB、did not believeC、could not belie

He suddenly called my name on the street, but I could not _____ where I had met h

Unfortunately he could not ______ the danger at that time.A、prepareB、pretendC、performD、p