My father _______ for London tomorrow， for there is______ an  important meeting there.

Li Rong told me what difficulties she had had  ______ English before she came to Canada.

________ warm at night, I would fill the woodstove, then set my alarm clock for midnight so I could refill it.

_____, she burst into tears.

After ________in the research for so many years，the scientist succeeded in finding the result at last.