你本来应该预料到的！英文怎么说？语法解释呢？为什么我想到了虚拟语态呢？

You should have anticipated that.

You should have anticipated that.
这个句子本就应该用虚拟语气，这原因是这个句子是说这话的人的一个猜测。

You should have realized that.

Should have done sth. 本该做某事（最后）却没有做。这种形式用在带if从句的虚拟式中时，表示一种虚拟语气，表示与过去事实的相反。此时if从句要用过去完成时。如：
If he had been here, he would have been glad to see you.
如果if从句用的是一般过去时的话，那么主句就要用would+动词原形（这种虚拟式构造）来表示虚拟语气，如：
If I were rich, I would travel around the world.

上面两种（should have done sth. 和would+动词原形），是表示虚拟语气比较常用的两种，以及would have done sth. 虚拟式的构造除此之外，还有很多，如Simple Present一般现在时，Present Continuous现在进行时，Present Perfect现在完成时，Present Perfect Continuous现在完成进行时，Simple Past一般过去时，Past Continuous过去进行时，Past Perfect过去完成时，Past Perfect Continuous过去完成进行时等等，楼主日后可以多注意。

至于预料这个词，你用anticipate之类都行。

You shoule have expected that.

You should have anticipated that. 是虚拟语气，表示说话的内容的一种假设，但现实是没发生的