I think Tom, as the head of a big department, should either study regularly or ____his job.
He traveled to many mountain villages and saw many poor children out of school. This experience ___________ his life.
I should very much like to have gone to the party but I _________.
My dictionary _________, I have looked for it everywhere but still ________ it.
The students ________ busily when Miss Brown went to get a book she ______ in the office.
By _____, water can be changed into gas.