问题补充:
I think Book 6 is than Book 5.
A. much difficult
B. very difficult
C. more difficult
D. the most difficult
答案:
A. much difficult
B. very difficult
(答案→)C. more difficult
D. the most difficult
解析:句意:我想Book 6比Book 5更难。than比,应用比较级,difficult的比较级是more difficult。根据题意,故选C。