When it cuts it leaves sticky ends or un-base paired single stranded regions on each end of the part its cut and that's just a property of many restriction enzymes; not all, some cut blunt,just right down the middle.

它切割后会留下两个粘性末端,或者未配对的单链部分,这是许多限制性内切酶的特性,但不是全部,有些限制性内切酶是从中间钝切的

耶鲁公开课 - 生物医学工程探索课程节选

If I cut both the plasmid and my DNA of interest with the same restriction enzyme I'm going to end up with the same sticky ends on both molecules.

如果用同一种限制性内切酶,来切割质粒和我感兴趣的DNA,在两个分子上就能得到同样的粘性末端

耶鲁公开课 - 生物医学工程探索课程节选