GRAMMAR - Modals of Can

English Grammar

Modals of Can

1) Can:

Spelling:

 

can, can't, cannot.

Uses: 

can has five possible uses: Ability, Permission, Negative deduction; GENERAL Possibility; particular possibility.

A/ Ability: 

Can in the sense of ability has three possible forms:

a/ Present: 

He can go (he is able to go).

b/ Past/Condition: type 2: 

He could go (he was able to go / he would be able to go).

c/ Condition: type 3: 

He could have gone (he would have been able to go).

All other tenses are formed with Be Able to, future: He will be able to....
Present: He has been able to...

B/ Difference between Was and Could: were able to: 

Sometimes there is no difference between Could and Was: were able to and both can be used without any difference in meaning. The only difference is that Could expresses general post ability (used past ability) whereas was able the expresses' Particular past ability and past achievement. It refers to ability in precise situation; in other words, I was able to do it = I could do it and I did it. It can be replaced by I managed to do it or I succeed in doing it.

Example:

a) He could drive very well when he was young. (General last ability).
b) Though he was tired, he was able to swim to the shore. (Particular past ability).

Remark:

In the negative form this distinction doesn't apply and couldn't be used for particular past ability.

Example in contrast:

- The box was locked, and I couldn't open it. (Particular past ability)

- Although the door was locked, I was able to open it. (Particular past ability).

B/ Permission: 

Can in the sense of permission has to forms:

1) Present/ Future: He can go (he may go, He is allowed to go, or he will be allowed to go...).

2) Past/ Condition. Type 2: He could go (He was allowed to go/ He would be All to go....).

All the other tenses are formed with BE ALLOWED To.

- Present perfect: She has been allowed to....

- Past perfect: She had been allowed to....

- Condition. Type 3: She would have been allowed to....

Examples:

Present: 

Affirmative: You can borrow my car if you want to (you may borrow it / I allow you t....).

Informative: (can = could = may).

a) can / could / may I borrow you dictionary? (Could is past form but the meaning is present).
b) yes, you can. (Don't say: yes, you could. Could is more hesitant that can, with could you are not sure you will get the permission.

Negative: (can't = mustn't)
c) you can't get into a mosque with your shoes on. (It's forbidden, you mustn't, you're not allowed....).

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