are these sentences true? if not, how are they used in daily conservations?
1) I took english courses before
2) i took english classes before
3) i went to english courses for years

Question

are these sentences true? if not, how are they used in daily conservations?
1) I took english courses before 
2) i took english classes before
3) i went to english courses for years

Answer

1) I took english courses before 
I took English courses before 
I have taken English courses before 
I have previously taken English courses

2) i took english classes before
See above

3) i went to english courses for years
I went to English courses for years
I have been going to English courses for years
I have been taking English courses for years

Answer

All of these sentences are technically correct. Classes and courses (in this case) are interchangeable for 1 and 2; they both mean the same thing. 
But, if you want it to sound more fluent, you "take courses" and "go to/went to classes"
Example:
1) I took English courses before
2) I went to English classes before
3) I took English courses for years

Answer

1) I took an english course before
2) is correct
3) i took part in english courses for a few years

Answer

All of these sentences are technically correct. Classes and courses (in this case) are interchangeable for 1 and 2; they both mean the same thing. 
But, if you want it to sound more fluent, you "take courses" and "go to/went to classes"
Example:
1) I took English courses before
2) I went to English classes before
3) I took English courses for years