People,especially teens,think it ______ great fun to surf on _______ Inter

问题描述:

People,especially teens,think it ______ great fun to surf on _______ Inter
A.a;the
B.不填;the
it是第三人称单数,为什么没有is或are也可以
要有解析

B
解析:fun不可数,great fun有趣的人(或事物)
is被省略了而已.