Modal verbs 情态动词

The modal verbs include can, must, may, might, will, would, should. They are used with other verbs to express ability, obligation, possibility, and so on. Below is a list showing the most useful modals and their most common meanings:

Modal             Meaning                                  Example

can               to express ability    表示能力                  I can speak a little Russian.

can               to request permission   请求许可         Can I open the window?

may              to express possibility 表示可能性              I may be home late.

may              to request permission 征求许可           May I sit down, please?

must            to express obligation   表示必须干某事            I must go now.

must            to express strong belief 表强烈的推测         She must be over 90 years old.

should         to give advice  给出建议                          You should stop smoking.

would          to request or offer    请求或给予                   Would you like a cup of tea?

would           in if-sentences                         If I were you, I would say sorry.

Modal verbs are unlike other verbs. They do not change their form (spelling) and they have no infinitive or participle (past/present). The modals must and can need substitute verbs to express obligation or ability in the different tenses. Here are some examples:

Past simple Sorry I'm late. I had to finish my math test.

Present perfect She's had to return to Korea at short notice.

Future You'll have to work hard if you want to pass the exams.

Infinitive I don't want to have to go.

Past simple I couldn't/wasn't able to walk until I was 3 years old.

Present perfect I haven't been able to solve this problem. Can you help?

Future I'm not sure if I will be able to come to your party.

Infinitive I would love to be able to play the piano.

Modals are auxiliary verbs. They do not need an additional auxiliary in negatives or questions. For example: Must I come? (Do I must come?×), or: He shouldn't smoke (He doesn't should smoke×).

Important: The explanations and examples on this page are just an introduction to this extensive and complex area of English grammar. Students of English who want to learn more should consult a good reference work, such as Swan's Practical English Usage.