25.　 C

24.　 D

23.　 C

22.　 B

21.　 C　 句中有连词that和谓语must be stimulated，缺少一个谓语动词，排除A,D，该句译成汉语是“有。。。的证据”,而不是“它是。。。的证据”所以排除B.

20.　 D on which to base his arguments in favor of the new theory = The professor will base his arguments in favor of the new theory on sufficient grounds.

19.　 B

18.　 C 该题空格处缺少的是连词，且在从句中作主语，所以排除A,D; that在名词性从句中只起连接作用。

17.　 A

16.　 D the results of which 等于whose results，是非限制性定语从句。