Japanese students work very hard but many are unhappy 里面的man

Japanese students work very hard but many are unhappy
句意：
中国学生学习很努力但是很多人都不开心.
这里的many,直接用作代词,意思是【许多人（这里指学生）】,意思就相当于【 many students】.
不过,你也可以把它看做是【 many students】后面省略了【students】,以避免重复.
祝你开心如意!