The modal verbs can, could in English are the present and past tenses of the same modal verb (translated in English as "to be able" or "could, could" in the past tense).
Feature of the verb
The modal verb can has only two forms: the first form (can) for all pronouns and nouns of all persons, for the singular and plural to express the present tense, and the second (its derivative) - the verb could is used with all pronouns and nouns denoting the subject, all persons in the plural and singular only in the past tense. There is no other form of could.
I could close the window. - I could (could) close the window.
Kate could read this dull journal. - Kate could read this boring magazine.
They could speak Japanese. - They could speak Japanese.
The difference between can and could
In addition to the fact that these two verbs are essentially two different forms of the same word in different time frames, there is another difference between them. Verb formscould in interrogative sentences express a more polite form of address. That is, the verb could in English is also a form of the subjunctive mood - Could you? - Could you? - Could you?
Could you close the window? - Could you please close the window?
Can you open the door? - Can you open the door?
The second sentence asks about the ability to perform an action. Whereas in the first sentence about the potential for doing the action. There is a difference and it is quite noticeable.
Examples with the verb could:
Could you complete the task? - Could you complete this task?
Could she cook the dinner? - Could she cook dinner?
Note:
- english word dinner, which is translated as "lunch" in school, in colloquial English means "dinner", but not in the home family circle;
- The "not" particle in the Russian translation of example sentences does not mean negation, but indicates a more polite form of request.
Usage rules
1) Modal verbs can, could are primarily used to express the ability and ability to perform an action in physical activity.
Could the girls paint like that before they started to study at an art school? - Could girls draw like this before they went to art school?
My cat could not climb a tree when it hurt the paw. - My cat (cat) could not (could) climbtree when he hurt his paw.
2) The verb could is past tense, but can be used in the present tense, as mentioned above, as a subjunctive mood.
Could you bring this notebook from the shelf? - Could you bring this notebook (notebook) from the shelf?
Could we stay here for the night? - Could we stay here for the night?
3) When in a sentence the verb could precedes the simple perfect tense, then we are talking about an event or action that should have happened or happened, but did not happen and did not happen.
We could have asked him but we were late. - We could have asked him, but we were too late.
4) Negative sentences with could in English. Such sentences are built on the basis of adding the negation particle not. to the modal verb form in the past tense.
They could not study at this university. - They couldn't study at this university.
She could not know the truth of this incident. - She couldn't know the truth about this incident.
My father couldn't come to this parental meeting. - My father couldn't come to this parent-teacher meeting.
5) Could is also used to make a sentence more emotional. In this color, the verb is used only in special questions and with the form of the infinitive and semantic verb corresponding to the sentence, which also depends on the time frame.
What could we be doing this room? - And what can we do in thisroom? (And what are we doing in this room?)
In this case, the emotional tone softens the strictly interrogative tone of the sentence.
Note:
in spoken English, short negative forms of the verb could not - couldn't are most often used
Exercise
Verb can, could: repetition and consolidation exercises.
1) In the first exercise, you need to insert words according to the meaning, following all the above examples and rules. Hint - take into account the translation of a particular sentence to calculate the correct answer to the task. You need to choose between the options: could - couldn't - can - can't.
- In my second year as a teacher, I almost lost my self-confidence because I () teach anything. - In my second year as a teacher, I almost lost my confidence because I couldn't teach anything.
- Nick tried hard to persuade him friend but he () change her mind. - Nick tried his best to convince his friend that he couldn't change his mind.
- Mary says she () speak six languages but she () talk to customers yesterday as she was a bit nervous. - Mary says she can speak six languages, but she couldn't talk to customers yesterday because she was a little nervous.
- Ted and her father () open the door because it was locked. - Ted and his father couldn't open that door because it was broken.
- I () finally talk to Lisa after I tried to reach her on the phone for hours. - Ifinally couldn't talk to Lisa after trying to call her for hours.
- You () memorize all of the rules in the past, you () do it now either. - You could remember all these rules in the past, and you can't do it now.
- My brother was the only one who () understand me, but now he () either. - My brother was the only one who could understand me, but now he can't either.
- Before the nuclear disaster in the 1943's, people () grow everything in their gardens. - Before the nuclear disaster in 1943, people could grow anything in their gardens.
- No matter how hard we try, we () see the difference in the two pictures our mother says she () easily see. - No matter how hard we try, we can't tell the difference in these two pictures that our mom can see right away.
- They () choose their opponents. The teams will be matched randomly. - They cannot choose their opponents. These teams are randomly selected.
2) Read the exercises carefully and try to determine which form of the modal verbs studied in this article can fit into the gaps (). Note that the potential answer is already in parentheses. You just need to understand whether it is correct or not. If not, what do you think is the correct answer for each particular sentence?
- It was really scary walking through the forest at night! I (can't) see a thing, it was so dark!
- We (could) see from an early agethat our daughter loved the water! She's a professional swimmer now.
- I would love to be brave enough to skydive, but I (can). I'm so afraid of heights.
- Of course you (can) bring your boyfriend to the party! He is very welcome.
- I (could) speak Japanese very well now as I learned the language when I was living there.
- (Couldn't) I finish work early today, please? I have a doctor's appointment I need to go to.
- Take your jacket with you. It (could) get cold later on.
Answers to the first exercise:
- couldn't.
- couldn't.
- can - couldn't.
- couldn't.
- could.
- could - can't.
- could - can't.
- could.
- can't - can.
- can't.
Answers to the second exercise with translation:
- Couldn't - It was very scary to walk through the forest at night. I couldn't see, it was so dark.
- We could see from an early age that our daughter loves water. Now she is a professional swimmer.
- Can't - I wanted to be brave enough to skydive, but I can't. I'm so afraid of heights!
- Of course you can take your boyfriend to the party. He will be welcome.
- C- I can speak Japanese very well as I learned Japanese while living there.
- Could - Can I finish work earlier today please? I have a doctor's appointment, I have to go. (Here it is appropriate to use the form can, but could in such a situation fits perfectly, as it expresses a more polite formquestion.)
- Take a jacket with you. It will be colder later.
