Present perfect vs. present perfect continuous

Complete the sentences with the correct form of the verbs in brackets: At last! I ___________ (solve) the problem.

What ______________ recently? (you / do) Anything interesting?

My brother ____________ (buy) a new motorbike. It looks great.

_____________ (you / swim)? Your hair looks wet.

Oh, There you are! I ____________ (look) for you everywhere.

Sorry we are late. How long _______________ (you / wait)?

I ____________ (know) Peter for a long time.

My friends _____________ (run) for two hours already.

I ____________ (never / understand) Maths and Physics.

The children are tired because they ___________ (play) all day.