For, since, while, during

FOR is used with a length of time .It answers the question HOW LONG .It can be used with all tenses .

He played with his sister for two hours .

He has played with friends for 3 hours .

She has been talking on the phone for a long time .

SINCE is used to specify the start of a period .It is often used with present perfect tense .

They have known each other since last school year .

He hasn't been to his country house since last autumn .

WHILE is used to talk about two actions that are happening at the same time .It is followed by a subject and a verb .It can be used with progressive and simple tenses .

We saw a lot of dolphins while we were surfing .

I will read this news while the baby has a nap .

While the baby sleeps ,I'll read my messages in my email box .

DURING is used when we talk about an event that happens WITHIN a period of time .It's followed by a noun and answers the question WHEN .

We could solve many difficult questions during last meeting .

The police arrested several suspected persons during the operation .