Can
Can is an auxiliary verb, a modal auxiliary verb. We use can to:
• talk about possibility and ability
• make requests
• ask for or give permission
Structure: Subject + can + main verb
Use of Can
Can: Possibility and Ability
We use can to talk about what is possible, what we are able or free to do:
• She can drive a car.
• John can speak Spanish.
• I cannot hear you. (I can't hear you.)
• Can you hear me?
Can: Requests and Orders
We often use can in a question to ask somebody to do something. This is not a real question - we do not really want to know if the person is able to do something, we want them to do it! The use of can in this way is informal (mainly between friends and family):
• Can you make a cup of coffee, please.
• Can you put the TV on.
• Can you come here a minute.
• Can you be quiet!
Can: Permission
We sometimes use can to ask or give permission for something:
A. Can I smoke in this room?
B. You can't smoke here, but you can smoke in the garden.
(Note that we also use could, may, might for permission. The use of can for permission is informal.)
Could
Could is an auxiliary verb, a modal auxiliary verb. We use could to:
• talk about past possibility or ability
• make requests
Structure of Could: Subject + could + main verb
Use of Could
Could: Past Possibility or Ability
We use could to talk about what was possible in the past, what we were able or free to do:
• I could swim when I was 5 years old.
• My grandmother could speak seven languages.
• When we arrived home, we could not open the door. (...couldn't open the door.)
• Could you understand what he was saying?
Could: Requests
We often use could in a question to ask somebody to do something. The use of could in this way is fairly polite (formal):
• Could you tell me where the bank is, please?
• Could you send me a catalogue, please?
Reference: http://www.englishclub.com/grammar/verbs-modals_can_3.htm
ไม่มีความคิดเห็น:
แสดงความคิดเห็น