Modal Verbs – Could/Couldn’t, Can/Can’t

Modal verbs are used to ask for permission, make a request, or express an ability to do something. The primary difference between these modal verbs is that “can” is used in the present situation, whereas “could” is the past tense of “can.”

Here are some examples:

• I can swim.
• I could swim when I was seven, but not anymore.

The above example shows how “could” can be used to express past ability.

Another difference between the usage of the modal verbs is that “can” is often used when you believe in the ability of someone to do something. On the other hand, by using “could,” you are making a polite request.

These examples should help to clarify:

• Can you pass me the pen?
• Could you give me your pen?

The first example shows that you expect the pen to be passed to you, while the second is a polite request that might or might not be turned down.

Using the negative modal verbs is as simple as adding “not” or the suffix -nt.

• Q: Can you swim?
• A: No, I can’t.