Modal verbsofdeduction

can

can’t

will /

won’t

shall may must

could would should might -

Is Sally at home now?

we use indicative tenses

to say what we know

Sally is at home now.

I know

we use modals when we

suppose, deduce, imagine

Sally must be at home now.

I suppose

the choice of modal verb says

how certain we are

Sally

must

will

may

might

won’t

can’t

be at home now.

Sally

must

will

may

might

won’t

can’t

be at home now.

I’m convinced

(even if I don’t

know)

Sally

must

will

may

might

won’t

can’t

be at home now.

I suppose

Sally

must

will

may

might

won’t

can’t

be at home now.

it’s possible

Sally

must

will

may

might

won’t

can’t

be at home now.

c.f. modal verbs

of possibility

(last lesson)

Sally

must

will

may

might

won’t

can’t

be at home now.

I suppose she

isn’t

Sally

must

will

may

might

won’t

can’t

be at home now.

I’m sure she isn’t

(even if I don’t

know)

notice the opposites

Sally must be at home now.

Sally can’t be at home now.

Sally will be at home now.

Sally won’t be at home now.

1. when we don’t know

Theymay

mighthave lost my letter.

Theymay

mighthave lost my letter.

it’s possible that

they have lost my

letter

Theymay

mighthave lost my letter.

‘may’ and ‘might’

mean the same