oxford_guide_to_english_grammar

12 MODAL VERBS PAGE 114
Ability: can, could and be able to • 98
Most people can swim.
Unreal situations: would • 99
Six weeks' holiday would be nice.
Habits: will, would and used to • 100
People will leave litter everywhere.
The verb dare • 101
I daren't go up on the roof.
OVERVIEW: the use of modal verbs • 102
91 Introduction to modal verbs
1 A modal verb is always the first word in the verb phrase. It always has the same
form and never has an ending such as 5, ingot ed. After a modal verb we put a bare
infinitive.
It will be windy. You should look after your money.
A modal does not have a to-infinitive after it (except ought).
NOTE
a Some modal verbs have a spoken weak form. •55(1)
You must give me your honest opinion.
b We can stress a modal if we want to put emphasis on its meaning.
You really must be quiet. (It is very necessary.)
You 'may be right. (It is not certain.)
c Will and would have the written short forms 'll and 'd.
2 Like the other auxiliary verbs (be, have and do), modal verbs are important in
negatives, questions, tags and so on. A modal verb can have not after it, and it
comes before the subject in questions.
Your desk shouldn't be untidy.
How should I organize my work?
. You should take notes, shouldn't you? ~ I suppose I should.
We do not use do with a modal. NOT HOW do I should organize my work?
3 A modal verb does not usually have a tense. It can refer to the present or the future.
Present: We must know now. The letter might be in my bag.
Future: We must know soon. The letter might arrive tomorrow.
For the past we use had to, was able to etc, or we use a modal verb + have.
Past: We had to know then. The letter might have arrived yesterday.
But in some contexts could, would, should and might are past forms of can, will,
shall and may.
I can't remember the formula. (present)
I couldn't remember the formula. (past)
We may have problems. (direct speech)
We thought we might have problems. (indirect speech)