He plays basketball very well. He must have practiced it a lot.
二 情态动词：can和be able to 等
1．Can 和be able to
1）当指能力时，can和be able to可以互换，但be able to比can更加正式但也不常用。 如：My brother can/is able to play table tennis very well.
2) 我们用can来谈论将来可能发生的动作。
如：Let s get some exercise. We can go and jog in the park.
be able to可以用在不同的时态中，可以后面直接接动词原形或放在另一个情态动词之后。 如：I m sorry I haven t been able to play tennis with you recently.
It s nice to be able to attend the lecture.
Wang Gong might be able to win the chess game.
4) can的过去式是could，be able to的过去式是was /were able to
如：He could swim across the river when he was young.
Mike was a good swimmer, so he was able to take first place in the competition.
2 shall和 will
1）我们通常用shall来表达承诺，用will来表达决心或决定。
如：Don t worry. You shall have the tickets for the games.
Liu Mei will go and buy the tickets for the games.
2) 在疑问句中，shall用于第一人称或第三人称提供帮助或提建议，will用于第二人称和第三人称询问意愿。
如：Shall we go swimming this weekend?
A group of students are waiting to see you outside. Shall they come in?
Will you go hiking with me in the mountain?
Will he pay for me?
3 mustn t和needn t
Mustn t用来表达让某人不做某事，needn t用来表达做某事没必要。
如：You mustn t miss this football match. It s very important.
You needn t watch the game if you don t want to.
4 need和dare
当用做情态动词时，这两个词常出现在否定句和疑问句中。这两个词还可以当做普通动词来用。
如：You needn t / don t need to go training if you feel tired.
Dare he/ Does he dare to dive into the water from the bridge?
第三单元
一 被动语态
1．主动语态和被动语态在意思上没有太大区别，可以互换。在主动语态的句子中，我们用动作的发出者作为句子的主语；在被动语态的句子中，我们用动作的承受者作为句子的主语。
如：Scientists designed a VR headset. A VR headset was designed by scientists.
2 被动语态的基本结构是：be+-ed （动词的过去分词），在不同的时态中，be的形式是不一样的。例如，在一般现在时态中，be是is或are；在现在进行时态中，be是is/am/are+being；
