Question

Complete the sentence using could/couldn't/can/can't with the given verb:
My grandfather was a very clever man. He________ (speak) five languages.
A. could speak
B. couldn't speak
C. can speak
D. can't speak

Answer 1

Hint: Could, couldn't, can and can't are all variable forms of the verb, can. Can is used to indicate a possibility or an ability.

Complete answer:
Can’t is the negative form of can. Could is the past form of can. Couldn’t is the negative form of could. The negative forms indicate that there is no possibility.
We infer from the given context that an ability is being expressed and hence, the sentence must be affirmative in nature. Thus, the negative verb forms will not be applicable. We also infer that the sentence must be in simple past tense as the preceding sentence is in the simple past tense too.
Let us now analyse the given options to find out the correct answer.
- ‘Could speak’ uses the simple past form of the modal verb, can. It conveys the ability to speak.
For example: He could speak in fluent English.
We observe that it correctly completes the given sentence and hence, we can say that option ‘a’ is the correct answer.
- “Couldn’t speak” uses the negative form of the modal verb, could. It conveys the inability to speak in the past.
For example: She couldn’t speak to her parents yesterday.
We observe that since it is a negative word and does not fit the context of the given sentence, it is not the appropriate answer to complete the given sentence. Hence, we can say that option ‘b’ is not the correct answer.
- ‘Can speak’ means the ability to speak. It is in the simple present tense.
For example: The little girl can paint.
We observe that it does not fit the context of the sentence as it is not in simple past tense. Hence, we can say that option ‘c’ is not the correct answer.
- “Can’t speak” uses the negative form of the modal verb, can. It conveys the inability to speak.
For example: He can’t go to the cafeteria during the office hours.
We observe that since it is a negative word and in present tense, it does not fit the context of the given sentence. Hence, we can say that option ‘b’ is not the correct answer.

> Therefore, the correct answer is option ‘a’ - ‘could speak’.

Note: One must understand that apart from subject and verb agreement, the verb must also fit the context of the given sentence.