同学你好，该知识点来自沪江网校《新概念英语第四册【天猫专享】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学晚上好：
1. 不定式to do表示动作没有发生或即将发生，且to do动作的执行者是句子的主语。动词不定式和它前面的名词或代词如果存在着逻辑上的主谓关系，动词不定式则用主动的形式；如果是动宾关系，则用被动形式。
The manager looks worried，many things to settle. 经理看上去很着急, 有这么多的事情要处理。
The four of us agreed on a division of labor, each to translate a quarter of the book.
我们四人同意分工干，每人翻译全书的四分之一。
Many trees, flowers, and grass to be planted, our newly-built school will look even more
beautiful.种上许多的树、花和草后，我们新建的学校看上去将更美。
2. 动词-ed形式表示动作已经结束，与-ed的主语构成被动关系。
He was listening attentively in class, his eyes fixed on the blackboard.
他上课专心听讲，眼睛紧盯着黑板。
The workers worked still harder, their living conditions greatly improved.
由于工人们的生活条件大大提高，他们工作得更起劲了。
The president assassinated, the whole country was in deep sorrow.
总统被谋杀了，举国上下沉浸在悲哀之中。
3. 动词-ing式往往表示动作正在进行，-ing的主语和动作构成主动关系.
The food being cooked, the boy was watching TV.小孩一边做饭，一边看电视。
The girl staring at him, he didn't know what to say.姑娘两眼望着他，他不知道说什么好。
Time permitting, we will go for an outing tomorrow.如果时间允许的话，我们明天去郊游。
4. 另外还有两种固定形式：
1) There being +名词（代词）如：
There being nothing else to do, we went home. 没有别的事可做，我们就回家了。
There being no further business, I declare the meeting closed. 没有再要讨论的事了，我宣布散会。
2) It being +名词（代词）如：
It being Christmas, the government offices were closed. 由于圣诞节的缘故，政府机关都休息。
It being a holiday, all the shops were shut.由于今天是假日，所有商店都关门了。

希望以上答案可以帮助到同学！
祝愿同学学习进步！