Вопрос по английскому языку:

Раскройте скобки и поставьте глаголы в правильную видовременную форму:
Most of the time he ( sit) _____ behind a desk , but this week he ( get)__ some practical experience offshore .
A lot of different nationalities (work)____ in the refinery , so sometimes people (have)__ problems communicating.
I (not understand ) ___ how this instrument (work )___ . Can you explain it to me?
I' m sorry , Mr.Peters isn't here . He(have )___ an Arabic lesson . He (always have ) ___ one on Monday evening.
He (enjoy)___ sport a lot . He (go)____ to the gym twice a week. He (train)___ for next month's marathon.