Can Could And To Be Able To Exercise
Understanding Modal Verbs of Ability in English
Modal verbs can be tricky for English learners, especially when expressing ability. The verbs “can,” “could,” and the phrase “to be able to” all express ability but are used in different contexts and tenses. This exercise guide will help you master these important expressions and understand when to use each one correctly.
Can: Present Ability and Possibility
“Can” is one of the most common modal verbs in English. It’s used to express:
Present Ability
“Can” indicates that someone has the skill or ability to do something in the present.
Examples:
– I can speak three languages.
– She can swim very well.
– They can solve difficult math problems.
Permission in the Present
“Can” is also used to ask for or give permission.
Examples:
– Can I open the window?
– You can use my computer if you need to.
– Students can leave when they finish the test.
Possibility in the Present
“Can” expresses that something is possible.
Examples:
– It can be very cold in winter.
– The situation can change quickly.
– This recipe can serve up to six people.
Important Rules for Using “Can”
| Rule | Example |
|---|---|
| Does not change form for person | I can, you can, he/she/it can, we can, they can |
| Negative form: cannot or can’t | I cannot (can’t) swim. |
| Question form: inversion | Can you help me? |
| No -s in third person singular | He can play guitar. (NOT: He cans play guitar.) |
| Followed by bare infinitive (without “to”) | I can speak English. (NOT: I can to speak English.) |
Could: Past Ability and Possibility
“Could” functions as both the past tense of “can” and as a modal verb with its own uses.
Past Ability
“Could” expresses general ability in the past.
Examples:
– When I was younger, I could run very fast.
– She could speak French when she lived in Paris.
– They could understand the lesson easily.
Polite Requests
“Could” is often used for more polite requests than “can.”
Examples:
– Could you help me with this bag?
– Could I borrow your pen?
– Could we meet tomorrow instead?
Possibility or Suggestion
“Could” can express possibility or make suggestions.
Examples:
– It could rain later today.
– We could try the new restaurant downtown.
– This could be the solution to our problem.
Key Rules for Using “Could”
| Rule | Example |
|---|---|
| Past general ability | I could swim when I was a child. |
| Negative form: could not or couldn’t | I couldn’t understand the professor. |
| Not used for specific past achievements | I was able to finish the race. (NOT: I could finish the race.) |
| Followed by bare infinitive | She could speak three languages. (NOT: She could to speak three languages.) |
To Be Able To: The Versatile Alternative
“To be able to” is more versatile than “can” and “could” because it can be used in all tenses.
Present Ability
Similar to “can” but can be more specific.
Examples:
– I am able to work from home now.
– She is able to understand complex theories.
– They are able to communicate effectively.
Past Ability (Specific Achievements)
Unlike “could,” “was/were able to” can express specific achievements in the past.
Examples:
– Despite the difficulties, I was able to finish the project on time.
– They were able to escape from the burning building.
– She was able to win the competition.
Future Ability
Used to talk about ability in the future.
Examples:
– I will be able to speak Japanese after I finish this course.
– She won’t be able to attend the meeting tomorrow.
– Will you be able to help me move next weekend?
Perfect and Continuous Forms
“To be able to” can be used in perfect and continuous forms, unlike “can” and “could.”
Examples:
– I have been able to improve my skills.
– She had been able to maintain her fitness level.
– They will have been able to complete the project by next month.
Forms of “To Be Able To” in Different Tenses
| Tense | Positive | Negative | Question |
|---|---|---|---|
| Present Simple | I am able to | I am not able to | Am I able to? |
| Past Simple | I was able to | I was not able to | Was I able to? |
| Future Simple | I will be able to | I will not be able to | Will I be able to? |
| Present Perfect | I have been able to | I have not been able to | Have I been able to? |
| Past Perfect | I had been able to | I had not been able to | Had I been able to? |
Key Differences Between Can, Could, and To Be Able To
Understanding when to use each expression is crucial for speaking English naturally.
Specific Achievement in the Past
For a specific achievement or accomplishment in the past, use “was/were able to” rather than “could.”
– Correct: I was able to solve the problem yesterday.
– Incorrect for specific achievement: I could solve the problem yesterday.
General Ability in the Past
For general ability in the past, “could” is more common.
– Correct: When I was younger, I could run for hours.
– Also correct but less common: When I was younger, I was able to run for hours.
Future Ability
For future ability, use “will be able to” since “can” and “could” don’t have future forms.
– Correct: I will be able to drive after I get my license.
– Incorrect: I will can drive after I get my license.
Practice Exercises
Now let’s practice using “can,” “could,” and “to be able to” correctly.
Exercise 1: Fill in the Blanks
Choose the correct form: can, can’t, could, couldn’t, or an appropriate form of “to be able to.”
1. _____ you hear the fireworks from your house last night?
2. Do you think you _____ write that report by Tuesday?
3. I _____ touch my toes when I was younger, but I can’t now.
4. Despite the heavy traffic, we _____ arrive on time for the meeting.
5. After taking lessons for a year, she _____ speak French quite well.
Exercise 2: Sentence Transformation
Rewrite these sentences using the word in parentheses.
1. I know how to swim. (can)
2. It was possible for her to finish the project on time. (able)
3. He had the ability to play the piano when he was a child. (could)
4. They will have the opportunity to travel abroad next year. (able)
5. She didn’t manage to solve the problem. (couldn’t)
Exercise 3: Error Correction
Find and correct the errors in these sentences.
1. I will can speak Japanese after I finish this course.
2. She cans drive very well.
3. They could win the championship last month.
4. He couldn’t to understand the instructions.
5. We are able swim in this lake.
Common Mistakes to Avoid
Using “Can” for Future
Incorrect: I can help you tomorrow.
Correct: I will be able to help you tomorrow.
Adding “To” After “Can” or “Could”
Incorrect: She can to speak Spanish.
Correct: She can speak Spanish.
Using “Could” for Specific Past Achievements
Incorrect: I could finish the marathon yesterday.
Correct: I was able to finish the marathon yesterday.
Using Present Form for Past
Incorrect: Last year, I can swim very fast.
Correct: Last year, I could swim very fast.
Answer Key for Exercises
Exercise 1 Answers
1. Could/Were you able to
2. will be able to
3. could/was able to
4. were able to
5. can/is able to
Exercise 2 Answers
1. I can swim.
2. She was able to finish the project on time.
3. He could play the piano when he was a child.
4. They will be able to travel abroad next year.
5. She couldn’t solve the problem.
Exercise 3 Answers
1. I will be able to speak Japanese after I finish this course.
2. She can drive very well.
3. They were able to win the championship last month.
4. He couldn’t understand the instructions.
5. We are able to swim in this lake.
Final Tips for Mastering Can, Could, and To Be Able To
1. Remember that “can” and “could” are followed by the bare infinitive (without “to”).
2. Use “was/were able to” for specific achievements in the past.
3. For future ability, always use “will be able to” instead of “can” or “could.”
4. Practice using these forms in context by creating your own sentences.
5. Listen for these forms in native English speech to better understand their natural usage.
By practicing these exercises and understanding the rules, you’ll be able to use “can,” “could,” and “to be able to” correctly and confidently in your English communication.