It's fun to do和It's fun doing的用法

It's fun to do和It's fun doing的用法,具体一点,要有例句. It's fun to do和It's fun doing的用法 It’s fun to do还是doing it's fun doing中的fun 是adj it's fun to do 是n .这种说法对吗? It's fun to do sth.中的fun什么词性 it's fun to be it's fun to do 换成 感叹句是what fun 还是 how fun It's fun 后面是跟doing sth.还是跟to do sth. it is fun to do 还是 doing? it is fun to do和it is fun doing区别 It's a fun to do sth.fun是不可数名词为什么还要加a? it is fun to do 与it is no fun doing 与 it is fun doing三者的区别是什