As or while
As and while are used to talk about two longer actions or situations that develop at the same time. They can be used with both simple and continuous tense forms.
While I worked in the garage, my wife cooked lunch.
She then did the dishes as I cleaned the car.
However, in situations like these, while is more common than as because as has several other meanings as well. For example, as can be used to show the reason.
Study the example given below. It can be interpreted in two different ways.
As my wife was busy working, I prepared dinner.
In this case, it is not clear whether as shows time or reason since both meanings are possible.
If as shows reason, the sentence will mean something like this: I prepared dinner because my wife was busy working.
If as shows time, the sentence will mean something like this: While my wife was busy working, I prepared dinner.
As or when
Both as and when can be used to talk about two short events that happen at the same time. In this case, these conjunctions are often used with just.
Alice came just when I was about to leave. I spent about ten minutes chatting with her and missed my bus.
OR Alice came just as I was about to leave.
As long as showing time
As long as can express time. It is used when we are comparing situations of similar duration.
The music concert lasted as long as the football match.
You can play as long as you want.
As long as: expressing condition
As long as may also express a condition. In this case, it is used as an alternative to provided that.
I won’t mind your coming late as long as you don’t wake me up. (= I won’t mind your coming late provided that you don’t wake me up.)