Помогите) Надо поставить в правильную форму. Alexander Graham Bell probably 0) didn't...

Помогите) Надо поставить в правильную форму. Alexander Graham Bell probably 0) didn't know at the
time that he 1) ........ (invent) one
of the most popular devices in modem history. In fact, he
2)........ (work) on a hearing
device when he 3)........ (stumble)
on the invention of the telephone.
Bell 4) ........ (try) desperately to find
some way to help deaf people hear and
communicate with others because he 5) ........ (live)
with his deaf mother and wife and 6) ........
(experience) deaf people's problems first hand. Bell went on to invent numerous other things, but we
7)........ (always/remember) him for bringing us the
telephone.

1 had invented
2 had been working
3 stumbled
4 tried
5 had been living
6 experienced
7 will always remember