Modal Verbs (and other expressions) to express Ability
Hello everyone! Today we are looking at ways of expressing ability.
Can is the modal verb used to talk about present ability.
I can swim.
Verb to be and able to are also used to talk about present ability.
I am able to swim.
In the present, able to is a little more formal than can, but they have the same meaning so it doesn’t matter which one you use.
Could refers to general ability in the past.
I could swim when I was three years old.
Was/ were able to(and managed to) express ability on a particular occasion in the past.
The criminal was able to escape from prison last night or The criminal managed to escape from prison last night.
You can’t say the prisoner could escape… because you are not referring to general ability but rather something that happened only once.
Was/were able to can also be used to talk about general ability so it is possible to say “I was able to swim when I was three years old.” You just need to remember that if you are talking about something that happened only once you can’t use could. There are exceptions to this rule!
Could is used for general ability in the past and in all situations, general and specific, with the following verbs: see, hear, smell, taste, feel(state verbs of the senses), remember and understand. It is not wrong to use was/were able for these uses, but could is more common.
One more important point! In the negative, couldn’t can be used in all situations, general or specific, with all verbs. Therefore, ‘The criminal couldn’t escape from prison last night’ is correct. Of course, so is ‘The criminal wasn’t able to escape from prison last night.’
If you add a time reference to indicate the future, it is also possible to use can to talk about future ability. E.g. I can help you with your homework tomorrow.
When you want to use the Present Perfect or Past Perfect use able to, you can’t use can or could. E.g. I have been able to drive for two years. Following a modal verb, also use able to.
E.g. 1. I might be able to come to your party on Saturday.
E.g. 2. I will be able to help you later. Of course, ‘I will can help you later.’ is wrong!! That’s all for now!
Check your understanding of language concerning ability by doing this quiz! Remember, it doesn’t matter if you use can or am/is/are able to in the present, so this quiz is only about past ability. Choose the correct answer, A or B. (Sometimes they are both possible but usually one is more commonly used than the other.)
A. She could stop the baby from swallowing the toy.
B. She was able to stop the baby from swallowing the toy.
A. I could finish my homework before dinner last night.
B. I was able to finish my homework before dinner last night.
A. He could swim by the age of 4.
B. He was able to swim by the age of 4.
A. When I walked into the kitchen I could smell the freshly baked bread.
B. When I walked into the kitchen I was able to smell the freshly baked bread.
A. The fireman could save the boy from the burning house.
B. The fireman was able to save the boy from the burning house.
A. Junaid was a good runner. He could run faster than anyone.
B. Junaid was a good runner. He was able to run faster than anyone.
A. Junaid hurt his leg yesterday so Shahid could beat him.
B. Junaid hurt his leg yesterday so Shahid was able to beat him.
A. I could taste that she had put too much salt in the soup.
B. I was able to taste that she had put too much salt in the soup.
A. I couldn’t open the bottle of wine.
B. I wasn’t able to open the bottle of wine.
A. He could remember all the vocabulary he had learnt during the course.
B. He was able to remember all the vocabulary he had learnt during the course.
1 B, 2 B, 3 A&B, 4 A, 5 B, 6 A&B, 7 B, 8 A, 9 A&B, 10 A
Notes:- Numbers 1, 2, 5 and 7 are all talking about ability on specific occasions so you must use was/were able to.
Numbers 3 & 6 are talking about general ability so could is the first choice but was able to is also possible.
Numbers 4, 8 and 10 are using verbs that always go with could. Although it’s possible to use able to, it doesn’t sound natural.
Number 9 is using the negative (couldn’t). The normal rules don’t work with couldn’t so you can use it to talk about the past in general (as with the positive) or a specific occasion (impossible with could.)