请问：happen的用法.eg:what happened,what's happen的区别

请问：happen的用法.eg:what happened,what's happen的区别 求what happen to...用法 happen to 的用法 happen的用法 happen 的用法 happen的用法. this is not always what happens but it is what should happen特别是what 的用法 happen的用法,尽量具体. 求happen的用法!happen是否有进行时态?看例题：Now watch carefully and see what -- -------- in the experiment.（happen） happen的用法具体的用法 happen用法what's happened to you What's happened toyou what happen to you what's happened to you happen 和take place 的用法区别 come about和 happen用法的区别 求：happen的用法,麻烦详细一点, What happen what happen what happened/what was happened/what is happened/what happen/what is happeniwhat happened/what was happened/what is happened/what happen/what is happening这些用法都有吗 请问Over在时间上的用法I can't tell you what will happen over the next four years. 这个Over具体表示什么意思呢?别告诉我是四年多,怎么看都不像.