before -ing and after -ing

[Jon]

Hello,

Are those correct?

before doing = before I did
after doing = after I did

thks !!

[Tortoise]

That those are right or wrong depends on the context, or the tense of the clause follows/is followed by before, after.

Examples:

Please turn all the lights off before leaving = Please turn all the lights off before you leave

Before going to bed, I had finished my homework = Before I went to bed, I had finished my homework

After finishing my homework, I went to bed = After I had finished my homework, I went to bed

Hope this helps.

[Jon]

Hello again,

In the sentence: "Please turn all the lights off before you leave"
Could I use "left instead of leave"?

Thanks !!

[Tortoise]

I think we can not use left instead of leave. You see, it's a direct sentence, one person is requesting someone else to remember to turn all the lights off, or it's a banner hung on the wall to remind everybody of turning the lights off (maybe to save electricty :) )

[1111166666]

You can't use left in this sentence as you are not talking about the past.

However, if you change the sentence around a bit you could use it (but it would have a different meaning)

Eg. Before he had left, he turned all the lights off. OR He turned all the lights off, before he had left.

[Edison_Chen_e_c]

Yes, it depends.

He went to play basketball after he finished his breakfast.
=He went to play basketball after finishing his breakfast.

If the subject is the same, then it's correct.

But if not, then you cannot say that.
He went to play basketball after she finished her talk with him.
=She finishing her talk with him, he went to play basketball.

Keep the two different subject.