In English, there are two phenomena that express the «skill», «ability» to do something — a modal verb can design and be able to. The modal verb can occur at an early stage of training, so we did not hesitate to use it in a speech as long-acquainted with him, but if you want to refresh your knowledge, then pay attention to the material of the article «The modal verb CAN (COULD)» , which describes in detail the modal verb. In addition, about what is a «modal verbs» you can learn from the general articles about modal verbs — «Modal verbs in the English language.» In the same article, we will focus on what is the difference between eating and can be able to. Both of these events represent an opportunity, the ability to do something, but there must be a difference between them?
The modal verb can / kæn / (past tense form could / kʊd /) is the most common of modal verbs. It is used with the verb without the particle to (can swim, can run, can read). Can — this is the only modal verb with which the negative particle not written together — sannot / kænɒt / (short form can not / kant /).
The verb can (could) have the following meaning: have a physical or mental ability, the ability to perform the action expressed by the verb, which can (could) combined.
The verb can in combination with verbs in the active voice (I can do) is translated into the Russian language «can», «be able» (I, know how to do). If you can go before the verb in the passive voice (It can be done), it is translated «can do», «can be done.» Consider the details on the examples:
He can speak English. — He is able to speak in English. (active voice)
He could run fast when he was 20. — He could run fast when he was 20. (active voice)
What can be done to help you? — What can we do to help you? (passive voice)
The house can be built here. — The building can be built here. (passive voice)
In affirmative sentences can also used in the following meanings:
- Permissions to perform an action.
You can go home. — You can go home.
You can use this phone. — You can use this phone.
- Expressions of regret that some action has not been implemented in the past, the possibility has not been implemented. Here we use could + Perfect Infinitive (have done).
He could have done it himself. — He could do it myself. (but did not)
You could have told me about it long ago. — Could you tell me about it for a long time. (but did not say)
In a negative sentence can not (can not and could not) translated as «can not» or «can not» and is used in cases sledyuschih:
- To express prohibition.
I’m sorry you can not park here. — I’m sorry, but you can not park here.
It can not be done. — It can not be done (this can not be done).
- To express doubts, surprise, disbelief, and will be translated as «can not be to», «incredible.» If we use the infinitives of verbs in the present tense (do — Simple, be doing — Continuous), we have in mind this time.
She can not be at home now. — Incredibly, she is now at home.
You can not be telling the truth! — It can not be that you speak the truth!
If we express doubt or surprise in the past, it is necessary to use a can / could + have done (Perfect Infinitive).
He can not have done it. — It can not be that he did so.
She can not / could not have said this. — It can not be that she said it.
- The combination can not but + verb translated «one can not», «I can not.»
I can not but agree with you. — We can not agree with you (I can not disagree with you).
One can not but admit … — can not be denied …
Let’s look at the use of can / could in interrogative sentences:
- In matters can / could be put in the first place.
Can you drive a car? — Can you drive a car?
Can you speak any foreign language? — Can you speak some foreign language?
- Also can in matters may express doubts, surprise, and then can the verb translated as «do» (if we use could, we express a greater degree of doubt). If the action relates to a past time, it is used can / could + have done (Perfect).
Can he be still working? — Is it still working?
Can you dislike the book — Do not you like this book?
Can / could they have left yesterday? — Have they gone yesterday?
- The verb can in matters may express request. In a more polite form used could.
Can / could I take your dictionary? — Can I borrow your dictionary?
Could / can you answer my questions? — Could you answer my questions?
Be able to
The verb can is equivalent to be able / eɪb (ə) l /, which is used with a particle to. In this combination, the auxiliary verb to be can take any necessary temporary shape:
- am / is / are present;
- was / were in the past;
- shall be / will be in the future.
Thus, this structure can be used at any time, unlike the can (could), we use only in the present or past tense.
Verb be able (to) indicates the possibility of making specific, individual actions at a particular moment. For example:
I am able to swim across this river. — I am able to swim across the river. (Now when you need it)
I can play basketball, but I’m not able to play today, I have hurt my arm. — I know how to play basketball, but I can not play today because I hurt my hand. (t. e. all I know how to play basketball, but in this particular situation, I can not)
He can help you tomorrow. / He will be able to help you tomorrow.
He could help you. / He was able to help you.
The only difference between can and able to is that when using the structure be able to emphasis the fact that the person is physically able to help or has the ability / skills. Thus, in the last example, a proposal could be translated as «it could help you,» but the second variant was able to more like «he was able to help you», «he had the opportunity.»
However, there are situations when you need to use that structure be able to. CAN is impossible to use in the future tense to refer to the possibility of physical or mental ability.
He will be able to walk in two months. — He can go in two months.
I’ll be able to speak Spanish fluently by the end of the year. — I can speak fluent Spanish by the end of the year.
We use the modal verb could to describe the ability of a general nature (general ability), but if someone has done something special (for example, to avoid an accident, and so on. D.), Then the use was / were able to be more suitable.
I was able to stop my car in time before slamming into a truck. — I was able to stop his car in time before crashing into a truck.
The most important thing that you must remember is that only severe cases of use are be able to the possibility of a situation of physical or mental capacity in the future tense, as well as realizovanna (or not) actions in the past. In other cases, more frequently can or could. In English, many such cases where there is a very fine line between the use of different grammatical structures, but must carefully and diligently, all of these cases can be stored. We hope that we could help you to understand the difference between can and be able to.