第二部分：英语知识运用
第一节：单项填空（共15小题；每小题1分，满分15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. In many places in China, ________bicycle is still _________ popular means of transportation ..
A. a; the B. /; a C. the; a D. the; the
22. Modern plastics can _________very high and very low temperatures, so they are used in many ways.
A. stand B. keep C. stay D. resist
