“如果...该多好啊”的英文如何表达

最简单的是 if only
例如if only i were you
但是要注意 后面要用虚拟语气 这里的i were you 因为事实上 我并不是你 所以 were是一个虚拟语气的表达 而不是用一般时态 i am you。

If only...

例：If only she would go with me.

that'll be great if...

If....so be nice

If... This much good