Gone are the days when Chinese people were ______. China is more powerful than ever.
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.
Mr. Green is said _____ an experiment to prove the new method of solving the problem when young.