September13,1931 is the day__ we’ll never forget.a.when b.on which c.on that d.that说明理由on which 和 that 的区别又是什么?

September13,1931 is the day__ we’ll never forget.a.when b.on which c.on that d.that说明理由on which 和 that 的区别又是什么? is is is is. is Is is is is is is is is she is fine.-----------is-----------? what is over is what is done is Whatever is,is good. whatever is,is good. September 18 ,1931 is the day____ we will never forget david is ruler is ()than tom is. were is baby?here is here is..