What fun it is 和How fun it is 后面加doing还是to do

it is fun to do 还是 doing? It is fun?到底是It is fun to do sth 还是It is fun doing sth?It is It is fun to do sth对,还是It is fun to doing sth what fun it is和how fun it is it is great fun +doing还是to do it is fun to do和it is fun doing区别 为什么能说What fun it is to do sth.却不能说How fun it is to do sth. it's fun to do 换成 感叹句是what fun 还是 how fun how fun it is to do … what fun it is to do… 为什么要用后者,fun如果当形容 It’s fun to do还是doing what a great fun it is to go fishing和what great fun it is to what fun it is to swim 为什么不能用how?