As 和while 有分別?

While you are there, can you get me some stamps?

以上這句無問題.

那麼:

As you are there, can you get me some stamps?有無問題?

說有問題的人認為, while 引導持續時間副詞, as引導非持續時間副詞.例:

While my mother was cooking, I was playing computer games.

As my mother knocked at the door, I was playing computer games.

但是, 事實上, as 也可取代while:

As my mother was cooking, I was playing computer games.

所以, As you are there, can you get me some stamps?是正確的.