问题补充：
In the opinion of Li Ming, a science student in that high school, physics is chemistry, but much easier than English.
A. as difficult a subject as
B. as a difficult subject as
C. a subject so difficult as
D. difficult as a subject as
答案：
(答案→)A. as difficult a subject as
B. as a difficult subject as
C. a subject so difficult as
D. difficult as a subject as
解析：
试题分析:句意：在李明这个高中理科生看来，物理是和化学一样难的学科，但是比英语要容易的多。当as、so、too等后面的形容词有被修饰的名词时，应该用：as/ so / too +adj +a /an +n. 的形式，答案选A。
