The government should do more to reduce crime.

Should is not as strong as have to and must.

Can/Could/be able to

We use can to say that something is possible or allowed, or that somebody has an ability to do something. We use can + infinitive (can do, can see etc.)

We can see the lake from our bedroom window.

Can you speak any foreign languages?

The word ‘play’ can be a noun or a verb.

The negative form of can is cannot or can’t

Can has only two forms: can (present) and could (past). So sometimes it is necessary to use be able to.

e.g. a) Maria can speak French, Spanish and English.

b)Applicants for the job must be able to speak two languages.

May/Might

We use the modal verbs "may" and "might" to talk about possible activities or happenings in the future:

e.g. I'm not sure I'll go to the party. I may be away.

Don't drop by at 7:20 PM. I might be watching TV.

Please, prepare something to eat. Mr. Johnson might be hungry.

We may not be able to go to school this week.

There isn't much difference between the two. So you can say:

"John might be at home" or "John may be at home".

"I may visit Mary" or "I might visit Mary".

Sentences formed with "might" are less likely to happen than those with "may". For example:

I may be away at 10 PM. (35% likelihood)

I might be away at 10 PM. (20% likelihood)

Of course, these figures may vary depending on the situation.

However, when the situation is unreal, only "might" can be used:

If I were a bit smarter, I might go to college. (The speaker won't become smarter, so the situation is unreal)

If you want to emphasize progression of a situation, you may use the continuous form of the verb after the modal.

Don't drop by at 7:20 PM. I may/might be watching TV.

Need (necessity)

The modal verbneed may be either a defective or a regular verb. As a defective verb need has only one form and combines with a bare infinitive. In reported speech it remains unchanged. As a regular verb it has the past indefinite form needed and regular negative and interrogative forms.

The defective form is mainly restricted to negative and interrogative sentences, whereas the regular verb can be used in all types of sentences and is therefore more common.

e.g. You needn’t do it just now.

The teacher said that we needn’t come.

Have to (obligation)

Have to is often grouped with modal auxiliary verbs for convenience, but in fact it is not a modal verb. It is not even an auxiliary verb. In the have to structure, "have" is a main verb. The structure is: subject + auxiliary verb + have + infinitive (with to)

In general, have to expresses impersonal obligation. The subject of have to is obliged or forced to act by a separate, external power (for example, the Law or school rules). Have to is objective. Look at these examples:

In France, you have to drive on the right.

Date: 2015-12-11; view: 1380