There is a natural phenomenon scientists call the greenhouse effect.
Discovery in a South African cave suggests that modern human behavior ____ much earlierthan ____.
Most people are aware that, ____ , the relationship between Hong Kong and the Republic of the Philippines will become poorer.
______ stable China-Japan relationship is in _____ interests of two countries, Asia and the world, participants in the Beijing-Tokyo Forum agreed on Sunday.
— Did you know any French before you arrived in Washington?— Never ______ it, actually.
---Do you think you can finish the project by five o’clock this afternoon?---_______. I’ll be busy with my term paper all day.