问题补充：
In my opinion, soccer is sport in the world.
A. most popular
B. popular
C. more popular
D. the most popular
答案：
A. most popular
B. popular
C. more popular
(答案→)D. the most popular
解析：句意：在我看来，足球是世界上最流行的体育运动。句中有in the world在全世界，有一个大的范围，故用最高级形式，故选D.
