Translation of "Identity" in Chinese

Is a common European identity possible?

欧洲人统一有可能吗？

We know the identity of Tom's killer.

我們知道了湯姆的殺手的身份。

A student should not lose sight of his own identity.

学生不该忽略自己的身份。

We need six tickets, two of them are student tickets, here is our student identity card.

我們要六張門票，兩張是學生票，這是我們的學生證。

A schedule is an identity card for time, but, if you don't have a schedule, the time isn't there.

时间表就是时间的一张身份证，但是如果你没有时间表，时间就不在那儿。