They are all senior students.

他们都是高中生。

This book is intended for senior students.

这本书是专为高中生设计的。

I heard the senior students singing in the hall.

我听见高年级的同学在礼堂唱歌。

Only senior students have the access to this reading-room.

只有高年纪的学生才能进这间阅览室。

Only senior students have the access to this reading room.

只有高年级的同学才能进这间阅览室。