By the time he was ten,Edison______experiments in chemistry.
Online paper-checking requires that more attention _______.
The TV sets made by our factory sell best, but 10 years ago no one could have guessed the place in the markets that they _______.
I’m afraid that it is you, ________ Bernard, _______ to blame.
Much to our surprise, the first performance was well _______.
They kept trying, and their efforts finally _______.