for sb to do sth

 该结构可用作主语、表语、宾语、定语、目的状语、结果状语、比较状语等。　　

For a child to do that job is just inconceivable. 让一个孩子做这项工作真是不可思议。　　

It is for you to decide. 该由你来决定。　　

I meant for you to eat, son. 我的意思是要你吃，孩子。　　

Is there any need for me to go? 我有没有必要去？　　

She opened the door for me to come in. 她开门让我进去。　　

The box is too heavy for me to carry. 这箱子太重了，我搬不动。　　

There’s nothing worse than for a person to ill-treat a child. 没有什么比虐待小孩更恶劣的了。