作动词：think,guess,conjecture,surmise,speculate,suspect,infer,presume,to figure out,作名词：to give a guess,to make a guess at,conjecture,speculation; supposition,to form conjectures,to make conjectures等
情态动词（could, should）+have done是表示对过去的虚拟，是虚拟语气的一种，有的人也称之为”责备结构“，因为译成中文意思有”本来可以；本来应该）。说话者用这个结构往往语气有懊悔之意。eg. I should have told you last night. 我本来昨晚上就应该告诉你的。你说的must have done确实是表示对过去的猜测。1、对过去的猜测eg. He must have hidden the ring in somewhere only he knew. 他肯定是把戒指藏到了只有他自己知道的地方。2、对现在的猜测eg.-Do you know where is our new classmate from? 你知道我们的新同学是哪里人吗？ - He must come from Beijing. I can tell from his accent 他一定是北京人，听口音可以听出来。3、对未来的猜测（一般用will,或其他的副词，maybe, certainly will...）eg. Maybe he will come tomorrow.没准他明天会来呢。
guess及物动词 vt. 1.猜测;推测[+(that)][+wh-][O2]Can you guess the height of the tree? 你能猜出这树的高度吗? I can guess what will happen next. 我能推测出接着会发生什么事。 2.猜中,猜对I guessed his thoughts. 我猜着了他的想法。 3.【美】【口】想,认为[W][Y][+(that)]I guess we'll have to wait a few more minutes. 我想我们得再等几分钟。 不及物动词 vi. 1.猜;推测[(+at/about)]We can only guess at the result. 我们只能猜测结果。 2.猜中3.想,认为名词 n. 1.猜测;推测[C]My guess is that it will rain tomorrow. 我猜明天会下雨。
天蝎兔兔
