Present
1) I go to gym three times every week
2) I'm going to gym right now
3) I've come to gym
4) I've been doing gym for five years
Past
1) I went to gym on Thursday
2) I was going to gym twenty minutes yesterday
3) I called my friend at half past one yesterday and said that we had gone to gym at three p.m.
4) My friend said yesterday that he had been living in UK for 2 years
Future
1) I will go to gym tomorrow
2) I will going to gym during twenty minutes
3) I will have finished my lessons by 4 p.m. tomorrow
Close... when you talk about "gym" as a location, you call it "the gym". Also, you need to write "the UK".
In the <em>Past</em> sentences, 2 and 3 are wrong. Sentence 3 is very wrong, in fact. Could you try again? In the <em>Future</em> sentences, try writing sentence 2 again. "Will going" is grammatically impossible in English. I'd suggest rethinking how the continuous tenses function, especially in tha past and future.
