How to use"as "
When I read and write English ,one of the most difficult word for me is " as ".
Because " as " has a lot of use .
And the use is all depends.
I try to search sample sentence by English dictionary every time .
But I can't understand enough.
I think " as " is surely convenient , but at same time, it is bother , especially for me !
Please tell me how to use it .

Question

How to use"as "
When I read and write English ,one of the most difficult word for me is " as ".
Because " as " has a lot of use .
And the use is  all depends.
I try to search sample sentence by English dictionary  every time .
But I can't understand enough.
I think " as " is surely convenient , but  at same time, it is bother , especially for me !
Please tell me how to use it .

Answer

There are generally two prominent uses for 'as':
1. Comparatively - something is as ____ as something else
E.G. He is just as good as her at tennis.

2. Consequence. Used similarly to 'since' or 'because'.
E.G. You'll need to see a doctor, as you are sick.

Hope that helps!