preposition

[Anonymous]

explain the differences in these sentences:
+/ She will have finished her work by 7pm
+/ She will have finished her work before 7pm
+/ She will have finished her work at 7pm

[Tdol]

+/ She will have finished her work by 7pm
+/ She will have finished her work before 7pm
Not much difference betwqeen these two- 7 is the limit. The second sounds as if she will have finished the work comfortably bbefore the limit, while the first could go up to the last minute.

+/ She will have finished her work at 7pm

This could be making an assumption now about an action that has finished- I know her timtetable and it's 7-15, so I can say this in answer to a question about her whereabouts.
:D

[RonBee]

+/ She will have finished her work by 7pm
+/ She will have finished her work before 7pm
Not much difference betwqeen these two- 7 is the limit. The second sounds as if she will have finished the work comfortably bbefore the limit, while the first could go up to the last minute.

+/ She will have finished her work at 7pm

This could be making an assumption now about an action that has finished- I know her timtetable and it's 7-15, so I can say this in answer to a question about her whereabouts.
:D

But is "She will have finished her work at 7pm" a sentence likely to be heard in actual use? It doesn't seem very probable to me.

8)

[Tdol]

Not really, but you might say 'She'll have finished her work at 7, so she'll be on her way home now.' Other than that, it's not very probable.