NIOS II里出现Could not find include file ‘system.h‘ on include paths.

Could not find include file ‘system.h’ on include paths

在把Quartus II工程转移到新的目录下后，打开NIOS II后会发现出现
Could not find include file ‘system.h’ on include paths 这个错误。

解决步骤：
1、找到Project -> Properties;

2、点击Properties后，找到Project References，点击后到下图所示界面；

3、如下图所示，勾选这两个框，然后点击“OK”；

4、重新编译NIOS II工程，编译后，问题解决。