When we talk abaout ability, we mean two things
First, we mean general ability. This is something that once you have learned you can do any time you want, like being able to read or swim or speak a language, for example
The other kind of ability is specific ability. This mean something that you can or can’t do in one particular situation. For example, being able to lift something heavy, or find somewhere you are looking for.
PRESENT : CAN / CAN’T (FOR BOOTH GENERAL AND SPECIFIC ABILITY)
– I can play the piano
– She can speak English
– He can’t drive- he’s too tired
– We can’t come now
– We use ‘can’ and ‘could’ to talk about a skill or ability
For example :
– She can speak six languages
– My grandfather couls play golf very well
– I can’t drive
PAST : COULD / COULDN’T ( FOR GENERAL ABILITY)
– I could read when I was four
– She coud speak French when she was a child, but now she has forgotten it
– He couldn’t dance at al until he took lessons
– My grandfather couldn’t swim
WE ABLE TO COULDN’T (FOR SPECIFIC ABILITY)
– When the computer crashed yesterday, I was able to fix it. (not ‘ I could fix it)
– She was able to pass the exam, even though she hadn’t studies much. (not ‘she could pass’)
– He called us because he couldn’t find the house
– I couldn’t open the window
COULD + HAVE + PAST PARTICIPLE ( AN ABILITY SOMEONE HAD IN THE PAST, BUT DIDN’T USE)
– I could have played the piano well but I didn’t practice enough
– We could have come earlier
– She could have studied law, but she preferred to become a secretary
FUTURE : WILL / WON’T BE ABLE TO ( GENERAL ABILITY)
– At the end of course, you will be able to make your own website.
– He won’t be able to speak Japanese in a week ! It wi take months.
CAN / CAN’T (SPECIFIC ABILITY)
– I can help yoy tomorrow
– I can’t come to the party
MODAL VERBS OF ABILITY
– The modal verbs of ability show just that ability
– Ability can be expressed in the past, present, or future. I can be an ability that was used over and over again, or something that was done just once, on a special, or rare, occasion
– The modal verbs of ability are can, could, and be able to
Can is used to talk about ability in the present or future
He can read well.
Could is used to talk about ability in the past
He could read well ehen he was younger.
Be able to is used to tak abut a certain, or particular, ability
He was able to read when he was 4 years old
** while could might be used in the last example, be able to emphasizes the early age at which he could read
Could have, followed by a past participle indicates an ability NOT used and ofte shoes disapproval
He could have called me! He didn’t
Could not have followed by a past participle indicates an ability didn’t exist in the past.
– I couldn’t have phoned you yesterday, because I lost my phone last week.
Be able to is used with other modals or when forming the ‘ing’ or ‘to’ infinitive forms.
You will have the satisfaction of being able to read my report.
Nobody will be able to read ehat you have written.
We use can or could with the senses verbs ; see, hear, smell, etc,. to say that someone is aware of something through their senses.
I can smell gas downstairs.
I could see a few stars in the sky last night.
I couldn’t hear what she said because of the noise.
The modals of possibility (may, might, can, could) mean something like : “The way I see/fell things in the present circumstances, it is possible that. For may and might, we should add (…if I have anything to do with it)
Could and might express remoteness of any kind (past time, unlikely occurrence, stiffness due to shyness or respect
May and might express a more personal involvement in the creation of the possibility (an extrictly personal opinion, or some kind of authority.
• There are many kinds of possibility: Probability , chances: This could be your lucky day (It is likely, possible that..) Theoretical possibility , options: We can be friends, if you want to. Ability : He can dance on his nose (He is able to..) Assumptions (logical possibility): This may well be the purse you lost Permission : Can I go to the cinema? –No, you may not . (You’re not allowed to..)
• Ability and Possibility Explanation Can is often used to express ability and possibility . Look at the following examples: Ability: Jim can sing well. Possibility: We can clean our apartment tomorrow. Negative forms: cannot or can not ; contraction–> can’t Andy can’t come to class tomorrow. Past ability and possibility: could and could not; contraction–> couldn’t When Tom was little, he could speak English and Spanish. Jerry couldn’t come to work yesterday because he was sick.
We use can’t to express that something is logically impossible
He can’t be Julio Iglesias, with that awful watch!
The meaning is kept in the perfect form:
She can’t have broken your washing machine. She wasn’t here yesterday. (Talking about past facts, we consider them impossible now)
Compare: She couldn’t break your washing machine. (Remote action in time: maybe she tried to break it but was not able to.) But we are not looking back from NOW. It is just a past action.
Perfect modals of possibility
One of the most common uses of perfect modals of possibility is for assumptions about the past: we look back on an action that happened before, but we consider it now. That is how we can discuss the possibility of past facts now, or make regrets:
It could have been a great opportunity. You could have been a bit more talkative!
Compare: It could be a terrific day for Man U.. (Now we think there is a remote chance that it will be a terrific day) It could have been a terrific day… (We now think that it was possible before that it was a terrific day . We assume that it is impossible now).
-He might have been trapped in the mud. (We now think so)
-He might be trapped in the mud. (action now, possibility now as well)
-They might be the winners. (present winners)
-They might have been the winners. (we think so now, but this sentence sometimes suggests they weren’t).
Sumber ; http://www.slideshare.net/51625678/possibility-ability