什么时候主语用动名词 什么时候用todo啊啊啊

若此动作的逻辑主语暗中有所指用to do,暗中无所指用doing
1.To see is to believe.暗示有人要撒谎.
2.Seeing is believing.只是一个普通的思想教育.
当动作为一次性具体性将要发生性时用to do,当动作为经常性反复性习惯性时用doing.
1.To climb that tall tree isn't difficult for him.爬那颗大树
2.Climbing trees is easy for him.经常爬树

动名词做宾语的及物动词(短语)有：advise,consider, avoid, mind, miss, suggest, finish, practise, imagine, enjoy, delay,escape, feel like, put off, insist on, give up, can’t help,stick to等。如：
I suggested taking a walk. 我建议去散步。
不定式作作宾语的及物动词有：afford,agree, ask, expect, hope, want, wish, manage, pretend, decide, determine,learn, offer, plan, refuse等。如：

He refused to go with us.他不愿意和我们一起去。