情态动词
情态动词本身有一定的词义,表示语气的单词。但是不能独立作谓语,只能和动词原形一起构成谓语。情态动词用在行为动词前,表示说话人对这一动作或状态的看法或主观设想
首先它是动词,而且不同于行为动词,行为动词表示的是可以通过行为来表达的动作(如写,读,跑),而情态动词只是表达的一种想法(如能,也许,敢)
(一)can
后面加动词原形,can的含义表示“能够,可以” e.g.I can do it
人称、单复数不影响can的形态。
e.g.She can do it.
e.g.Students can do it
否定形式can’t
can的否定形式直接加not,缩写是can't
can't的含义表示“不能够,不可以” e.g.I can't do it
e.g.She can't do it.
e.g.Students can't do it
一般疑问句→_→can提句首
e.g.She can bring some juice.→_→Can she bring some juice?
(二)must
后面加动词原形,must的含义表示“必须,必要” e.g.You must come in time.
人称、单复数不影响must的形态。
e.g.She must come in time.
e.g.Students must come in time.
否定形式mustn't
一般疑问句→_→must提句首
肯定回答:Yes,人称+must
否定回答:No,人称+needn't
e.g.Must I finish my homework before eight o'clock?
Yes,you must/No,you needn't