第二部分英语知识运用（共两节，满分45分）．
第一节 语法和词汇知识（共15小题；每小题1分，满分15分)
从各题所给的四个选项(A、B、C和D)中，选出最佳选项填入空白处。
21. Historically, ______ main material for making tables has been wood, but ______ metal and stone have also been used.
A. the; / B. /; / C. the; the D. /; the
22. Good news! We didn’t spend ______ we had expected.
A. as half much money as B. much money as half as
C. as much money as half D. half as much money as
23. I had planned for the house closer to a river, but I was told there was a danger of flooding.
A．built B．be built C．being built D．to be built
