REMINDER: NOT A TEACHER
(1) This is what Mr. Michael Swan in his popular book Practical English Usage
(a) We use a present tense if the meaning is future:
"I will telephone you after I arrive. (My comment: You could also say "After I
arrive, I will telephone you."
(b) We often use the present perfect to show that one thing is completed
before another starts:
"I will telephone you after I have seen Jake." (My comment: You could also say "After I have seen Jake,I will telephone you.")
(2) It is only my opinion that you could say:
(a) After you dig the hole, put the tree in it.
(b) After you have dug the hole, put the tree in it.
(3) In my opinion, probably most native speakers would use "a" in regular
conversations because it's shorter and gets to the point faster; you might want
to use "b" in writing.
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