Just because you major in English, don't think that you will have mastered real English.
不要以为你是英语专业的就能精通“真正”的英语。
This is a bill.
这是一张账单。
I'm not sure. I ought to do some studying, as I've got masses of work to do, but I think I'll be too tired. Maybe I'll just watch the news on television and go to bed early.