To keep safe为什么要用to

Question

如题所述

Answer 1

动词不定式作主语时，句子的谓语动词常用单数。
把不定式置于句首。如：
To get there by bike will take us half an hour.骑自行车到那儿将花费我们半个小时。
To make up for lost time is not possible.要弥补失去的时光是不可能的。
To lean out of the window is dangerous.身子探出窗外很危险。
To save money now seems impossible.现在好像不可能存钱。

Answer 2

To keep safe
为了，表示目的