English Grammar in use

 

Can, could and be able to

WE use can (do) to say that something is possible or something has the ability to do something. The negative is can’t (cannot). You can hear the noise made by the children hundred metres away. Can you speak any local language? I am afraid I can’t come to work on Saturday.

Be able to is possible instead of can, but can is more usual. Are you able to speak any foreign language? But can has only two forms: can (present) and could (past). So sometimes you have to use be able to: I haven’t been able to clean my house recently. (can has no present perfect). Richman might not be able to come tomorrow. (can has no infinitive).

Could and was able to: Sometimes could is the past of can. We use could especially with these verbs: see, hear, smell, taste, feel, remember and understand. When we went into the kitchen area, we could smell burning meat. She spoke in a low voice but I could understand what she was saying.

We also use could to say that someone had the general ability to do something. My brother could speak four languages. When Simon was 10, he could ride a bicycle on his own. But if you mean that someone managed to do something in one particular situation, you have to use was/were able to (not could): The fire spread through the building very quickly but everyone was able (=managed) to escape. (not could escape).

Compare could and was able to in this example: Ralph was an excellent chess player, He could beat anybody. (=He had the ability to beat anybody.) But once he had a difficult game against Alfred. Alfred played very well but Ralph was able to beat him. (=He managed to beat him in this particular game.) The negative couldn’t is possible in all situations. – My grandfather couldn’t swim. We tried hard but we couldn’t persuade him to change his mind.

In this exercise you have to use can or be able to. Sometimes it is possible to use either; sometimes only be able to is possible. Examples: Mary has travelled a lot. She (or is able to) speak four languages. I haven’t been able to sleep very well recently. Reuben . . . drive but he hasn’t got a car. I can’t understand Jacob. I’ve never . . . understand him. I used to . . . stand on my head but I can’t do it now. Ask Lee Anne about your problem. She should . . . help you.

In this exercise you have to complete the sentence with could . . . Example: I can’t sing now but . . . I could sing very well when I was a child.

He can’t play tennis very well now but he . . . quite well when he was younger. She can’t run very fast now but when she was at school she . . . faster than anyone else. I can’t swim very far. These days but ten years ago I . . . from one side of the lake to the other.

This time you have to answer the questions with was/were able to. Example: Did you persuade them? Yes. It was difficult but we were able to persuade them. 1. Did they find your house? Yes. It took them a long time but they . . . . . . . 2. Did you win the match? Yes. It wasn’t easy but I . . . . . … 3. Did the thief escape? Yes. The policeman chased the thief but he . . . . . . .

May (have) and might (have). Study this example situation: You are looking for Martin. Nobody knows for sure where he is but you get some suggestions: He may be on the clerk’s office. (= perhaps he is in the clerk’s office) He might be having lunch.(= perhaps he is having lunch). Ask Ryan. She might know. (=perhaps Ryan knows).

We use may and might to say that something is possible. There is no important difference between may and might. He may be in the clerk’s office or he might be in the clerk’s office. The negative is -may not and -might not (or mightn’t): Ryan might not be in the clerk’s office. (= perhaps he isn’t in the clerk’s office) I’m not sure whether I can lend you any money. I may not have enough. (= perhaps I don’t have enough.

Study the structure: I/you/he/ et cetera. (may/might) (not) (be in his office/be having/waiting) (know/have/do etc.

There are many more such structures and examples. Study and understand them for improved performances in your work.

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