英语复杂长句中see sb do sth的用法与理解

问题描述

When I finished it the night was half gone and there was no time left to compose a proper, respectable essay for Mr. Fleagle. There was no choice next morning but to turn in my tale of the Belleville supper. Two days passed before Mr. Fleagle returned the graded papers, and he returned everyone's but mine. I was preparing myself for a command to report to Mr. Fleagle immediately after school for discipline when I saw him lift my paper from his desk and knock for the class's attention.

老师：您好！

这段原文用的都是过去时态，所以我不明白为何在最后一句中用的是动词原 knock，我觉得有点疑惑。是否是因为“看见某人做某事”是 see sb. do sth. 所以，这里用的是动词原形 knock? 因为 knock 前面有个 and，是并列关系的缘故？

我这样理解正确吗？

烦请老师指导。多谢。

老师答疑

灰老师：

1. 主句结构和成分
【I 主句主语】【was preparing 谓语】【myself for a command to report to Mr.Fleagle immediately after school for discipline宾语】【 when I saw him lift my paper from his desk and knock for the class's attention 时间状语从句】
主体句子结构是【sb be doing sth when sth happened】
2. 从句结构和成分
when 【I从句主语 】【saw 谓语】【him宾语】【 lift my paper from his desk and knock for the class's attention省略不定式符号to的不定式短语,宾补】

这里的 lift 和 knock 的动作是同时进行的，两个动词表示并列关系。

黎老师：

你的理解是正确的，即：when I saw him lift my paper from his desk and knock for the class's attention.（lift...和knock...是并列的不定式短语，作saw的宾语补足语）