It was in the lab ________was taken charge of by Johnson ________they did the experiment.
Readers can______quite well without knowing the exact meaning of each word.
You are______your time trying to persuade him;he’ll never join us.
—You didn’t invite John to the party?—______him,too?
She told me that her father______to the post office when I arrived.
By the time he was ten,Edison______experiments in chemistry.