问题补充：
I have worked with him for some time and have found that he is than John.
A. more efficiently a worker
B. a more efficient worker
C. more an efficient worker
D. a worker more efficiently
答案：
A. more efficiently a worker
(答案→)B. a more efficient worker
C. more an efficient worker
D. a worker more efficiently
解析：考查了在含有than的比较级中名词的位置，即a/an＋比较级＋名词。
