New words (for me) in English and queries regarding verb tenses

I decided to write on the blog the new words and expressions that I learn in English and, if I have time, to form sentences with them so that I can remember them.

mostly                    as good as gold

shelves                   though

cabinets                 appearance

involves                 errand

apron                    siblings

drawing                 hugely

naughty                 neither do I

I need to know why we use in English 2 tenses for verbs if they express the same type of action. I will give two examples, because they show more clearly what I want to find out.

  1. We all live in Dundee, except my sister; she’s 19 and is studying at university.

we live and she studying

 

2. Even when I lose I winning.

I lose and I winning

Can someone to explain me why we don’t use “we live” and “she studies” or “we are living” and “she is studying”?