Grammar Bite #26—Use of can and could

11 April 2013

 

What’s the difference between these two sentences?

·      How can I improve my English?

·      How could I improve my English?

 

Ability and Possibility

The fundamental difference between can and could is the difference between what someone or something is able to do (can) and what is possible (could).

 

Modals: can & could

The words can and could are called modal auxiliary verbs. They both combine with a main verb, for example, can improve or could improve.

 

·    The modal can is used to show ability. For example, I can type 100 words per minute. (ie, I am able to type 100 words per minute.)

 

·    The modal could is primarily used in two ways:

1.    To express past ability as the past tense of can (When I was younger, I could type 100 words per minute, but now I can type only around 80 words per minute.)

2.   To show possibility (I could meet you next Tuesday at 3pm.) In this case the speaker expresses a time when it’s possible to meet.

 

The two sentences above are very close in meaning: someone is asking for suggestions on how to improve their English. But they do convey a slightly different tone.

 

Objective

The first question (How can I improve my English?) could be seen as more objective and straightforward. The tone is more direct.

 

If someone I’ve never met asked me that question, I might say something like, To improve your writing, you can read lots of books, newspapers and magazines.

 

Subjective

The second question (How could I improve my English?) is a bit more subjective and tentative. The tone is more polite-sounding and indirect.

 

To answer that question, I might say, To improve your writing, you could read lots of books, newspapers and magazines.

 

Conditionals

Both can and could are also used with conditional clauses.

·      If you work out often, you can lose fat and build muscle.

·      If you work out often, you could lose fat and build muscle.

 

The differences here do not relate to tone. By using can, the speaker is guaranteeing that you will lose fat and build muscle if you work out often. By using could, the speaker says that it’s possible to lose fat and build muscle if you work out often, but they won’t guarantee it.

 

 

 

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