The time--- I spend on math is much more than on English A that B when C at which D during which

A that为什么不选b因为选that的话，that = the time，则：I spend the time on math.是成立的。若选when，则：I spend when on moth.是不成立的。关系代词是指代先行词的，这里，出题人设下了一个陷阱，让考生误以为time这个名词是指时间，而错选。