问题补充：
He listens to the teacher as as your cousin.
A. careful
B. carefully
C. care
D. cares
答案：
A. careful
(答案→)B. carefully
C. care
D. cares
解析：句意：他听老师讲课跟你的堂兄一样认真。A. careful 认真的，形容词； B. carefully 认真地，副词； C. care关心，照顾，动词。 D. cares 关心，照顾，动词。修饰动词短语listens to the teacher，用副词，as carefully as和......一样认真。故选B。
