情态动词

Modals

can, could, may, might, should, had better, must, will, would

Phrasal Modals

have to, have go to, ought to, be able to

Phrasal modal changes depending on the subject.

Rule #1

Modals DO NOT change.

Rule #2

subject

modal / phrasal modal

main verb(Keep original verb form!)

-s -ing -ed

Review

Modals are helping verbs.

Use original verbs with modals.

Ability in the P resent and Future

present	subject	can (not)	main verb
past	subject	could (not)	main verb

Present and future

I	am (not) able to	main verb
You, We, They	are (not) able to	main verb
He/She/It	is (not) able to	main verb

Past

I/ He/ She/ It	was (not) able to	main verb
You, We, They	were (not) able to	main verb

can’t and couldn’t

These modal verbs express impossibility or disbelief in the present.

My mom can’t be at the door.She’s traveling to another country. It’s imposible!

For impossibility and disbelief , can’t and couldn’t have the same meaning.

It can’t be my neighbor , or it couldn’t be my neighbor . He’s at work right now.

Can’t and couldn’t show that someone is not 100% certian.

I can’t see who it is, so I don’t know for sure. however, I’m almost certain it isn’t my mom or my neighbor.

Like other modal verbs , can’t and couldn’t will come before the simple form of the main verb . With this use , the main verb is almost always be.

It can’t be my new phone in this box. The box is much too big.