第二部分英语知识运用（共两节，满分50分）
第一节 单项填空（共20题，每小题1分，满分20分）
从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。
21. They argued for hours on _____ end until the meeting came to ______ end at last, reaching no agreement.
A. an; / B. /; an C. an; an D. /;/
22. Mr. Smith, ______ to experience different culture, set off on his journey to South America last week.
A. determine B. to determine C. determined D. being determined
23. The government has taken some measures to reduce pollution, but it maybe some time ______ the situation improves.
A. since B. when C. unless D. before
24. In the back of the garden, we found the little girl ______ with both hands ______ up with a rope.
A. lying; tying B. lay; tied C. lying; tied D. laid tying
