Daivid was surprised at the bird's change, and he was just to ask what had made such a surpring为什么要用"to ask"
问题描述：
Daivid was surprised at the bird's change, and he was just to ask what had made such a surpring
为什么要用"to ask"
答
be to do表将来 在这里就是“他就要去弄清楚、、、”的意思
答
be to 结构，后接动词原形，表示将要发生的动作，“大卫对小鸟的变化的感到吃惊，他准备问问是什么造成了这种惊人的变化”。
答
有两个动词啊,何况be to do 表示将要做某事.
答
The enemy gave in finally .最终敌人屈服了。但如果说向某人屈服，则用介词to来连接。因为give in 是 vi，不及物动词，不能直接加宾语。所以这里用give