本来准备明天去见你的，但你不在线’的英语怎么说

see :表示看的结果，meet:表示遇见，相见。
on line：一般是指电话类的连线。
on-line:adj.在线的，即时的。这个词一般是指计算机、铁路、航空运营类。

个人认为此句用meet 更适合。

I am going to meet you tomorrow,but you were not on-line.

I planed to meet you tomorrow, but you were not on internet.

I was going to see you tomorrow,but you were not on line.