"future perfect" - (not my title!)

woodcutter · Post by **woodcutter** » Sun Apr 24, 2005 9:00 am

From another forum:

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.

The grammar guru said that the meaning is fairly equivalent but that the 3s are slightly different, that 3-3 is not used, and that the other 3s (as well as 'we need to have finished by next week') are awkward. I don't find them awkward. Do you?