◆课后作业
Ⅰ 单项填空:从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。
1.At _________ time does the salesgirl get up late in the morning. She is too busy to take a good rest.
A. no B. any C. each D. one
2._________ gravity holds things together, some unknown _________ is working across the universe to pull everything apart.
A. While; force B. When; power C. As; energy D. Since; strength
3.Liu Xiang is_________ first Chinese who has won_________ one-hundred-metre hurdle gold medal in the Olympic Games.
A. the; a B. the; the C. the; an D. a; the
