Complete with the verbs between brackets in the passive voice (present simple or past simple)

The telephone is a device which (use) million times every day. It seems so incredible that you can speak into the receiver and your words (hear) on the other end. Nowadays, communication (make) very quickly and messages (send) all around the world.

But what (know) about Alexander Graham Bell, the man which the telephone (invent) by?

Bell (born) into a family who were specialists in teaching elocution. He (train) and (teach) by his father and grandfather. In 1864 Bell (employ) as a master in Elgin's Weston House Academy in Scotland. His first studies in sound (conduct) here and the idea of transmitting speech with electricity . (conceive)

His family moved to Canada in 1870 after his two brothers (kill) by tuberculosis. After spending some time in Boston, lecturing and demonstrating the Visible Speech system which (invent) by his father.
In 1872 his own school to train teachers for the deaf , (open) He continued studying and teaching until he (make) a Professor at the University of Boston. However the idea of transmitting speech along a wire never left him, a device (develop) with a simple receiver in which electricity (turn) into sound.
On 6 April 1875, Bell (grant) the patent for his telegraph, but his work (finish) on his telephone. The final breakthrough (cause) by an accident that occurred while he was working on a circuit with one transmitter and two receivers on 2 June 1875. The transmitter (switch) off and Watson, his assistant, was adjusting one of the receivers when Bell heard a note coming from the receiver in his room. With the transmitter turned off, the note had to be coming from the other receiver. He had discovered that the receiver could also work in reverse: instead of making sound when electricity (send) through it, it also made electricity when it (supply) with sound because the sound moved the magnet in the coil and electricity was generated. More importantly, the electricity (vary) with the voice.
His system (develop) and (submit) for patent on 14 February 1876. The patent (grant) on 7 March. Within a year the first telephone exchange (build) in Connecticut and The Bell Telephone Company (create) in 1877, with Bell the owner of a third of the 5,000 shares. Stock in the company soared from $50 to over $1,000 a share within three years.
Alexander Graham Bell was not yet 30 years old.