21. As nobody here knows what is wrong with the machine, we must send for an engineer to ______ the problem.
A. handle B. raise C. face D. present
【解析】选A。考查动词词义辨析。句意：因为没有人知道机器到底出了什么毛病，我们必须派人去请工程师来处理这个问题。handle the problem符合题意。
22. In the reading room we found her ______ at a desk, with her attention _____ on a book.
A. sitting; fixing B. sit; fixed
C. seated; be fixed D. seated; fixed
【解析】选D。考查宾补。句意为：在阅览室里我们发现她坐在桌子边，全神贯注地读书。seat为及物动词，表示状态要用be seated；with her attention _____ on a book是with结构作伴随状语，fix one’s attention意为“集中注意力”，attention与fix之间是逻辑上的被动关系，用过去分词作宾补，故答案选D。
