J5110499Trego ©Roland Trego 11/04/99 rev. 11/24/2013 5:00 PM

Single-Word Modals and Periphrastic Modals

We have already seen many single-word modals (modal aux-words).

can could would should may might must will won’t shall

There are also modals composed of several words. These are called periphrastic modals.

1. Single-word modal: can (ability)

Periphrastic modal: be able to

am

is

are able to

was

were

Same meaning: I can help him. I am able to help him.

2. Single-word modal: may (permission)

Periphrastic modal: be allowed to or be permitted to

am

is

are allowed to

was permitted to

were

Same meaning: You may not smoke in restaurants in this state.

You are not allowed to (you are not permitted to) smoke in restaurants.

3. Single-word modal: must (need, necessity, obligation, or duty)

Periphrastic modal: have to

Same meaning: Excuse me, but I must go now. Excuse me, but I have to go now.

Important: You cannot have two consecutive single-word modals (连续的, consecutivos, подря́д).

The second one must change to a periphrastic modal.

Wrong: I passed my test, so next semester I �will can� take Level 7.

Right: I passed my test, so next semester I will be able to take Level 7.

Wrong: Before you go to Level 5, you �must can� write yes/no questions.

Right: Before you go to Level 5, you must be able to write yes/no questions.

Exercise 1: Change the single-word modals to periphrastic modals. The meaning of the new

sentences will be the same.

a. I can’t help him right now. > I am not able to help him right now.

1. I must be there by 4:00. >

2. She’s only two and a half, and she can read!

3. They may not watch TV until they have finished their homework.

>

4. The little boy couldn’t tell the police what his parents' names were.