第二部分 英语知识运用(共两节，满分45分)
第一节 单项填空（共15小题；每小题1分，满分15分）
21. ［2012福州模拟］ ______ successful launch of Tiangong-1 on September 29th marked ______ significant step in our country’s plan to build a space station．
A. The; a B．/; a C．A; the D．/; the
22. You have to study harder, ______ you will fall behind others.
A. or B. but C. so D. and
23. When you feed horses, watch that one ______ — it bites.
A. particularly B. actually C. usually D. naturally
24.［2012桐城模拟］Taobao is Asia’s largest retail（零售的） network platform, ______ people can buy and sell many kinds of things．
A. where B. when C. that D. whose
