Ⅱ. 单项填空（共15小题; 每小题1分, 满分15分）
21. ________you have known it, there is no need to keep it a secret.
A. Now that B. Unless C. If case D. Though
【解析】选A。句意：既然你知道了, 就没必要保密了。now that既然; unless”除非”; though“尽管”。
22. _______she couldn’t understand was _______fewer and fewer students showed interest in her lessons.
A. What; why B. That; what
C. What; because D. Why; that
【解析】选A。主语从句缺少宾语, 故选what; 根据句意“她所不能明白的是为什么越来越少的学生对她的课感兴趣。”所以, 表语从句须由why引导而不能由because引导。
