It really is a long time since I was last a student. 这句话里面的last是什么成分,这是正常语序么?

问题描述:

It really is a long time since I was last a student. 这句话里面的last是什么成分,这是正常语序么?

这句话没语病么?个人觉得怪怪的,It has been really a long time since last time when I was a student .个人一件仅供参考