what在句中的用法
1. He also helped develop what came to be known as the social news website Reddit.
2. This belief is what eventually got him in trouble with the law.
第一个问题：请帮忙分析一下1.2.这两句中what是怎么用的吧,这是一种特别的结构吗?
3. He believed the Internet should be used to make that knowledge available to everyone.
4. He helped develop that Internet publishing technology when he was only 14.
第二个问题：3.4.两句中的that可以省略掉吗?加上或者不加有区别没?
谢谢!