Could (do) və could have (done)

Could modal felindən bir çox hallarda istifadə etmək olar. Bəzən could modal felindən can modal felinin keçmiş forması kimi istifadə etmək mümkündür:

• Listen. I can hear something. (now)
• I listened. I could hear something. (past)

Amma ondan yalnız bu cür istifadı edilmir. Could modal felindən həmçinin indi və ya gələcəkdə olması mümkün olan hərəkətlər haqqında danışmaq (xüsusən ehtimal etmək) üçün istifadə etmək olar. Məsələn:

• A: What shall we do this evening?
  B: We could go to the cinema.
  
  
• It's a nice day. We could go for a walk.
• When you go to New York next month, you could stay with Barbara.
  
  
• A: If you need money, why don't you ask Karen?
  B: Yes, I suppose I could.
  

Yuxarıdakı cümlələrdə can moadal felindən istifadə etmək də mümkündür.

Could modal felindən əslində dediyinizin həqiqətdə mümkün olmadığını bildikdə işlədə bilərsiz:

• I'm so angry with him. I could kill him! ('I can kill him' -- yox)

Could modal felindən həmçinin nəyinsə indi və ya gələcəkdə mümkün olduğunu bildirmək üçün istifadə olunurı

• The phone is ringing. It could be Tim.
• I don't know when they'll be here. They could arrive at any time.

Yuxarıdakı cümlələrdə can işlətmək mümkün deyil. ('It can be Tim' -- yox).
Yuxarıdakı cümlələrdə could modal felinin mənası might modal felinin mənasına oxşardır:

The phone is ringing. It might be Tim.

Could (do) və could have (done) ifadələrini müqayisə edin:

• I'm so tired. I could sleep for a week. (now)
• I was so tired. I could have slept for a week. (past)

Could have (done) ifadəsindən çox zaman mümkün olan, amma baş verməyən hadisələr haqqında danışmaq üçün istifadə edilir:

• Why did you stay at a hotel when you went to New York? You could have stayed with Barbara. (= you had the opportunity to stay with her but you didn't)
• Jack fell off a ladder yesterday but he's all right. He's lucky - he could have hurt himself badly. (but he didn't hurt himself)
• The situation was bad but it could have been worse.

Bəzən could 'would be able to...' mənası verir:

• We could go away if we had enough money. (= we would be able to go away)
• I don't know how you work so hard. I couldn't do it.

Could have (done) = would have been able to (do):

• Why didn't Liz apply for the job? She could have got it.
• We could have gone away if we'd had enough money.
• The trip was cancelled last week. Paul couldn't have gone anyway because he was ill. (= he wouldn't have been able to go)
• You did very well to pass the exam. I'm sure I couldn't have passed it. (= I wouldn't have been able to pass it if I had taken it)