Topic: Modal Verbs

Day 1. Overview

Modal verbs (情態動詞) are sometimes called ‘modal auxiliaries’ (情態助動詞). They are used together with the main verb to express manner or mood – for example, possibility, permission or obligation. 情態動詞與主動詞 (main verbs) 連用來表達語氣的狀態

Note: Modal verbs cannot be used as the main verbs!

Wrong: I will happy forever! (Modal verb ‘will’ is not the main verb and thus cannot be used by itself.)

Correct: I will be happy forever! (Modal verb ‘will’ has to be used with main verb ‘be’.)

Read the two paragraphs below. Which one is more expressive(富有表達能力)?

Do you stop watching TV? You’re supposed to do your best and you are able to finish your homework before your dad starts scolding you again. If you just concentrate on getting finished, you are allowed to dine outside. You know your dad does not let you go out if you don’t get the work done. You are lazy.

Would you stop watching TV? You’re supposed to do your best and you should be able to finish your homework before your dad has to start scolding you again. If you could just concentrate on getting finished, you might be allowed to dine outside. You know your dad will not let you go out if you can’t get the work done. You must not be lazy.

Paragraph 2 is more expressive (富表達力) than paragraph 1, right? The modal verbs are used to help express possibility (可能性), permission(許可), suggestion(建議), request(請求), prohibition(禁止), obligation(義務), necessity (需要性), ability (能力), etc.

Modal verbs:

can, could, shall, should, may, might, will, would, must, have to (should)

Special grammatical features of Modal Verbs

1. After a modal verb, the verb will never change.

Category	Modal and structure
Present	She may dream about you. Modal verb + bare infinitive
	They may dream about you. Modal verb + bare infinitive
Past	She might dream about you. Modal verb (past tense) + bare-infinitive

2. A modal verb indicates the tense of the sentence, but not the main verb.

Tense	Wrong	Correct
Simple Present	She mays dream about you. She may dreams about you.	She may dream about you.
Simple Past	She may dreamt about you. She mayed dream about you.	She might dream about you.

2. Some modal verbs can be used as the past of the other modal verbs.

Present	Past
Can	could
shall	should
may	might
will	would
must	had to (There is no past tense form of must; ‘have to’ is used to express obligation in the past.)

Usage of Modal verbs

1. Statements

Positive statements

She can swim.

Negative statements

à We do not need to add do or did when making negative statements. The correct negative statements should be:

She cannot swim. (‘Cannot’ is a single word)

She could not speak French when she was young.

Note; You may have made the following mistakes.

l She can not swim.

l She doesn’t can swim.

l She didn’t can speak French when she was young.

2. Questions

You may have made the following mistakes:

* Do you can swim?

* Don’t you should leave?

à We do not need to add do or did when forming questions. The correct questions for the above two statements should be:

Can you swim?

Shouldn’t you leave?

3. Question Tags

Tag questions are used when the answers are supposed to be known. They are used to emphasize the facts or the actions.

When the answer is positive, a negative modal verb should be used.

She can swim, can’t she?

He should apologise, shouldn’t he?

When the answer is negative, a positive modal verb should be used.

They cannot speak French, can they?

They would not offend you, would they?