subject + can + base verbUse can for ability in the present. The main verb stays in the base form, with no to and no ending.
Ability: Can, Could, Be Able To
A2Use can for ability now, could for general ability in the past, and be able to in future, perfect, and more formal structures.
What you'll learn
- Say what someone can do now with can + base verb.
- Talk about general ability in the past with could.
- Use be able to in future and perfect forms.
- Build negatives with can't, couldn't, and not able to.
- Ask questions by moving can, could, or be before the subject.
- Use time markers to choose can, could, or be able to.
Structure
subject + could + base verbUse could for general past ability. The main verb stays in the base form.
subject + be + able + to + base verbUse be able to when the sentence needs another tense or a fuller verb phrase.
subject + can't/couldn't/isn't able to + base verbUse can't or couldn't with a base verb, or use not inside be able to.
Can/Could/Will + subject + be able to + base verb?Put the modal or be-word before the subject to make a question.
Build a sentence
Subject
Verb
Shecandrive
She can drive now.
After can, do not add to and do not change the verb.
When to use
Ability now
Talk about what a person knows how to do or is free to do in the present. Maria can drive. We can meet after lunch.
General ability before
Describe a skill or ability someone had in an earlier period. At twelve, Tom could fix a bike and cook dinner.
Future ability
Say what will become possible later. After the course, Lisa will be able to give presentations in English.
Formal style
Choose be able to in careful or formal wording. Our team will be able to answer all questions by Friday.
Markers
nowat the momentwhen I was tenin the pastnext yearafter the coursesince then
Common mistakes
Wrong
Maria can to swim very well.
Correct
Maria can swim very well.
After can, use the base verb with no to.
Wrong
Tom can swims fast.
Correct
Tom can swim fast.
After can, the main verb stays in the base form.
Wrong
Lisa will can drive next year.
Correct
Lisa will be able to drive next year.
Use be able to after will. English does not use will can.
Wrong
Do you can swim?
Correct
Can you swim?
Questions with can do not use do. Put can before the subject.
Wrong
You will be able to finish on time?
Correct
Will you be able to finish on time?
Future questions start with will, then the subject.
Common misconceptions
❝ I can use can in every tense if the meaning is ability. ❞
Can does not build every tense. For future and perfect forms, use be able to instead.
❝ Could is just a stronger or more advanced form of can for any time. ❞
Could often points to past ability or a polite question. It does not replace can in every present sentence.
Skills in this rule (7)
CAN_FOR_PRESENT_ABILITYw5Use can for present ability
Use can to say that a person knows how to do something or is free to do it now. Put can before the base verb.
COULD_FOR_PAST_GENERAL_ABILITYw5Use could for general ability in the past
Use could for something a person was able to do in general in an earlier time. It describes past ability, not one successful action at one moment.
BE_ABLE_TO_FOR_OTHER_TENSESw5Use be able to when can or could does not fit the tense
Use be able to for future forms, perfect forms, and other structures where can or could is not the right choice. Change be to match the time: will be able to, have been able to, was able to.
NEGATIVES_WITH_CANT_COULDNTw4Make negatives with can't, couldn't, and not able to
Put not after can or could, or inside be able to. The main verb stays in the base form after can, could, and able to.
QUESTIONS_WITH_CAN_COULD_BE_ABLE_TOw4Ask questions with can, could, and be able to
Put can or could before the subject for direct questions. With be able to, move be before the subject or use will before the subject in future questions.
FORMAL_CHOICE_BE_ABLE_TOw3Choose be able to for more formal or careful wording
Use be able to when you want a more formal style or when the sentence needs a full verb phrase. It often appears in announcements, work messages, and careful writing.
TIME_MARKERS_FOR_ABILITYw3Recognize time markers that guide can, could, or be able to
Look for cues like now, at the moment, when I was ten, next year, and since then. These markers help you choose present, past, or future ability.