+0
Hello, teachers!
Can we use these sentence with basically the same meaning in each group?

1-1. We should finish this by next week.
1-2. We should have this finished by next week.
1-3. We should have finished this by next week.

2-1. We could finish this by next week.
2-2. We could have this finished by next week.
2-3. We could have finished this by next week.

3-1. We can finish this by next week.
3-2. We can have this finished by next week.
3-3. We can have finished this by next week.

Thank you very much.
1 2
Comments  
Within each group of three, the first two have the same meaning, and the third does not mean the same thing as the first two.

The third sentence in each group has a counterfactual meaning, but a meaning which goes poorly with the future-oriented adverbial "by next week".

We should have finished this (but didn't) ?by next week.
We could have finished this (but didn't) ?by next week.

"can have", in the sense intended in 3-3, is not used.

CJ
Thank you very much as always, Jim!

How about this sentence? Is this also awkward?
- We need to have finished this by next week.
Teachers: We supply a list of EFL job vacancies
Yes, I would place it in the 'awkward' category. It seems to be a roundabout way of saying "We need to finish this by next week", the structure preferred by native speakers when expressing this thought.

CJ
I've got it!
Thank you very much, Jim.
Enjoy the chirping of the birds!
I'm not sure - I don't think the latter example is especially awkward.

The only one which bothers me or strikes me as especially different out of any of them is "We can have finished this by next week".
Students: Are you brave enough to let our tutors analyse your pronunciation?
Thank you very much, woodcutter, for your comment.

May I ask you why you exclude the sentence "We can have finished this by next week"?

Regards.
I'm afraid I'm having analysis failure. Perhaps simply because the past participle "finished" does not go smoothly with "can" (can have this finished being OK because the focus is then on have)? I do very much feel that your latter example is OK though. Anyone agree?
Hello Woodcutter

Do you feel any difference between "I need to finish it by next week" and "I need to have finished it by next week"?
If there's no difference I would go with the simpler one.

[Google hits]
need to finish it by 336 hits
need to have finished it by 8 hits

paco
Students: We have free audio pronunciation exercises.
Show more