Modal verbs – to be able to
The construction to be able to is used in all forms, in the present tense (am/is/are able to), the past (was/were able to) and in the future tense (will/shall be able to). This construction means “to have the necessary physical strength, mental power, skill, time, money, or opportunity to do something”. After to be able, the infinitive is used with the particle to. The construction be able to is close in meaning to the modal verb can, but we use it when we talk about a single action, for the performance of which it was necessary to make an effort.
Be able to is not used for long-lasting or permanent actions. Let’s consider the main examples of the use of to be able to:
- Ability, opportunity to do something (at a certain time):
- Today I am able to stay with you
- I have some problems, but I am able to go there
- Realized opportunity in the sense of “successful”, “to be able to” in time:
- I was able to get in touch with him
- I was able to persuade him
- In the future to express physical or mental ability:
- I’ll be able to speak to him tomorrow
- They’ll be able to help you
- I’ll be able to speak Spanish in half a year
- After modal verbs:
- You have to be able to tell the difference between “good” and “evil”
- You should be able to measure costs