二:情态动词是很难把握的一个语法,复习的突破口应该以句式和人称作为复习的依据,要注意以下几个方面：(难点探究-----师生互动)
1. 情态动词表推测的局限性:can,may,must在表推测时有其局限性
1)can不用于肯定句; can用于否定句和疑问句.
Can / could that really be true? / / He can’t / couldn’t have slept well through all that noise.
2)must不用于否定句和疑问句; must只用于肯定句, You must be hungry after all that walking . / I’m sorry she’s not here. She must have left already.
3)may不用于疑问句 ; may用于陈述句和否定句. I may be late so start without me. /There may have been an accident. / Who knows what will happen. You may even have married by then. / $ 50 may not be enough.
▲对于其它表推测和可能性的情态动词might, could, would, should等则没有句式的限制,只是语气不同而已. must, may, might表推测语气逐渐减弱.
The road may/ might / could be blocked .
It should be a good movie--- its reviews were very good.
