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. ---Xi Jinping,______ vice-president of China was on ___ visit to the United States several days ago.
---Yeah, it is said that the visit was _____ great success.
A.X; a; a B. X ;X ; a C. the ;a ; X D. the ; X ; X
22. Mrs. White found her husband surrounded by letters and papers and ________ very worried.
A. look B. looked C. looking D. to look
