Not only ________learn a foreign language, but also ______ master it well.

Women , to air pollution before giving birth to a baby, are more likely to give birth to children with heart defects, researchers reported on December 29.

I don’t like winter _____ it’s too cold.

Will you please repeat your idea?—SureBut I don’t think that you ________ attention

30．When you finish your work, don’t forget to put the tools back where they ________