Question

i (practise) ... the guitar when he came home
we (not/cycle)... all day
while alan (work) ... in his room, his friends (swim) ... in the pool

Answer 1

was playing
haven't been cycling
was working\ were swimming

Answer 2

I was practising the guitar when he came home.
We were not cycling all day.
While Alan was working in his room, his friends were swimming in the pool.