)) два предложения past perfect continues, два предложения future perfect continues.
желательно не "простенькие".

Объяснение:

I had been writing for 2 hours when he came home.

we had been cleaning up the room until 5 o'clock.

I will have been working at this factory for 20 years by the end of the summer.

Mary will have been studying English for 2 years by the time you return.