这是从句的省略，我在以前的回答中解答过多次。

一共2种形式，

1：主动 something + that/who/which +动词原形/动词第3人称单数/be动词 就可以省略为something + 动词ing形式

2：被动 something + that/who/which +be+动词的过去分词 就可以省略成something + 动词过去分词

例子： Many students are more motivated to do homework using online resource. 其实就是 Many students, who use online resource, are more motivated to do homework.

你会经常看到这个 This book put on the table is mine. 其实完整形式就是this book which is put on the table is mine.