Is my use of the tenses below correct:
-things are beginning to change now. cruises to the Antractic cost a lot. however,more and more tourists go on them. Unfortunately,this tourism has started to cause problems.Scientific studies show that the tourists now are destroying the ecosystem of the Antractic .for example the number of some species of wild life have gone down rapidly.
But you really should learn to punctuate. This isn't optional. The first letter of a sentence is capitalised, and you must use the right spacing around periods and commas.
I've noticed this a lot in posts from Arabic speakers. And I've asked this question before, but haven't received an answer - Aren't you taught about punctuation? How do you become this proficient in English without learning how to put a space around a comma?
(I'd be grateful if anyone could answer this).