Expressing ability with CAN, COULD and BE ABLE TO – English grammar video lesson

In this English Video Lesson Alex is explaining the use of such modal verbs as /Can/, /Could/ and /Be able to/ in talking about “ability” in various tenses – past tense, present tense and future tense.

CAN and COULD are generally used in many cases and situations such as making requests and asking for permission, but this video lesson specifically focuses on “ability” – having the skill, power or means to do something.

CAN is used in the present and in the future tense form, but could never be used in the past form. The important rule is that the verb that follows CAN should be in its base form (infinitive without the “to” particle). It’s wrong to say “I can to swim” or “I can swimming”. You must say and use only basic form of the verb “I can swim”!

COULD is used to describe the possibility or ability in the past.

There is one specific exception to the use of  COULD in the past form. Could cannot be used when you’re talking about specific achievements in the past. In this case it’s more appropriate to use BE ABLE TO.

For example: My brother was able to pass the math test.

BE ABLE TO could be used in the all the tenses – past, present and future.

Examples:

Present	I can swim, but I can’t dance. I can help you tomorrow. I am able to drive the car.
Past	My grandma could swim. I was able to drive the car.
Future	I will be able to drive the car.