the student always have fun singing English songs.为什么是singing
问题描述：
the student always have fun singing English songs.为什么是singing
答
have fun doing sth. 开心地做某事
没有have fun to do sth结构
答
HAVE FUN DOING STH 是固定的句子
答
singing English songs你可以当作状语,主语重复时可以动词ing形式充当状语,还原状语从句就是The student always have fun when he(she)sings English songs.另外,如楼上所述,have fun doing sth.意思做某事很开心....