2018-2019学年译林版高中英语选修7学案:句型剖析 Unit2 
2018-2019学年译林版高中英语选修7学案:句型剖析 Unit2 第2页

It was long before... 过了好久才......

It is not long before... 过了不久就......

It won't be long before I come back.

不久我就会回来。

He walked a long time before he stopped.

他走了很久才停下来。