I'll never forget the factory ___ (that/which) I worked five

I'll never forget the factory ___ (that/which) I worked five I'll never forget the factory ___ (what/which) I worked five i'll never forget the holidays ( ) i worked in the factory I'll never forget the day on which I worked with you. I’ll never forget the time when (=on which) we worked on the that is the day ( ) I'll never forget.A.which B.on which c.i I’ll never forget the days___in which__ we worked together. 1.I’ll never forget the days we worked together. I’ll never forget the days _____________ we worked together I will never forget the days (when/that/which)we worked toge I'll never forget the days that/which we spent together. I’ll never forget ___ you for the first time.