Modal Use
1. Present 2. Past 3. Future
Negative Forms
You can also use:
can general ability
1. I can speak Chinese
2. SHIFTS TO "COULD" I could speak Chinese when I was a kid.
3. SHIFTS TO "BE ABLE TO" I will be able to speak Chinese by the time I finish my course.
1. I can't speak Swahili.
2. SHIFTS TO "COULD" I couldn't speak Swahili.
3. SHIFTS TO "BE ABLE TO" I won't be able to speak Swahili.
to be able
can ability during a specific event
1. With a burst of adrenaline, people can pick up cars.
2. SHIFTS TO "BE ABLE TO" With a sudden burst of adrenaline, he was able to lift the car off the child's leg.
3. SHIFTS TO "BE ABLE TO" With a sudden burst of adrenaline, he will be able to lift the car.
1. People can't pick up cars.
2. SHIFTS TO "BE ABLE TO" Even the weight lifter, couldn't lift the car off the child's leg.
3. SHIFTS TO "BE ABLE TO" Even three men working together won't be able to lift the car.
can opportunity
1. I have some free time. I can help her now.
2. SHIFTS TO "BE ABLE TO" I had some free time yesterday. I was able to help her at that time.
3. I'll have some free time tomorrow. I can help her then.
1. I don't have any time. I can't help her now.
2. SHIFTS TO "BE ABLE TO" I didn't have time yesterday. I wasn't able to help her at that time.
3. I won't have any time later. I can't help her then.
can permission
1. I can drive Susan's car when she is out of town.
2. SHIFTS TO "BE ALLOWED" I was allowed to drive Susan's car while she was out of town last week.
3. I can drive Susan's car while she is out of town next week.
1. I can't drive Susan's car when she is out of town.
2. SHIFTS TO "BE ALLOWED" I wasn't allowed to drive Susan's car while she was out of town last week.
3. I can't drive Susan's car while she is out of town next week.
may
can request
Can I have a glass of water?
Can you give me a lift to school?
(Requests usually refer to the near future.)
Can't I have a glass of water?
Can't you give me a lift to school?
could may
can possibility / impossibility
Anyone can become rich and famous if they know the right people.
Learning a language can be a real challenge.
(This use is usually a generalization or an supposition.)
It can't cost more than a dollar or two.
You can't be 45! I thought you were about 18 years old.
could
could possibility
1. John could be the one who stole the money.
2. John could have been the one who stole the money.
3. John could be charged with the crime when the police finish the investigation.
1. Mary couldn't be the one who stole the money.
2. Mary couldn't have been the one who stole the money.
3. Mary couldn't possibly be charge with the crime after the police examine the evidence.
might, may
could conditional (can, could)
1. If I had more time, I could travel around the world.
2. If I had had more time, I could have travelled around the world.
3. If I had more time this winter, I could travel around the world.
1. Even if I had more time, I couldn't travel around the world.
2. Even if I had had more time, I couldn't have travelled around the world.
3. Even if I had more time this winter, I could travel around the world.
could suggestion
1. NO PRESENT FORM
2. You could have spent your vacation in Hawaii.
3. You could spend your vacation in Hawaii.
NO NEGATIVE FORMS
could past ability
I could run ten miles in my twenties.
I could speak Chinese when I was a kid.
I couldn't run more than a mile in my twenties.
I couldn't speak Swahili.
be able to
could polite request
Could I have something to drink?
Could borrow your stapler?
Couldn't he come with us?
Couldn't you help me with this for just a second?
can, may, might
had better recommendation
1. SHIFT TO "SHOULD" OR "OUGHT TO" People should unplug toasters before they clean them.
2. SHIFT TO "SHOULD" OR "OUGHT TO" You should have unplugged the toaster before you tried to clean it.
3. You had better unplug the toaster before you try to clean it.
1. SHIFT TO "SHOULD" OR "OUGHT TO" People shouldn't clean toasters without unplugging them first.
2. SHIFT TO "SHOULD" OR "OUGHT TO" You shouldn't have cleaned the toaster without unplugging it first.
3. You had better not clean the toaster until you unplug it.
should, ought to
had better desperate hope/ warning
The movie had better end soon.
They had better be here before we start dinner.
(Desperate hopes and warnings usually refer to the near future.)
They had better not be late.
They had better not forget Tom's birthday gift.
"Had better" is often simply pronounced as "better" in spoken English.
Patrusiak