I think Jack does his homework than his sister.A. carefulB. more carefullyC. carefullyD. m

问题补充：

I think Jack does his homework than his sister.

A. careful

B. more carefully

C. carefully

D. more careful

答案：

A. careful

(答案→)B. more carefully

C. carefully

D. more careful

解析：句意；我认为杰克做作业比他的姐姐更细心。结合语境及下文，可知用副词carefully的比较级，修饰do，故选B。