答对,I will never forget the day -- we spent together.A.which

答对,I will never forget the day ＿＿ we spent together.A.which B.when C.on which D.where （选A,为什么?）I will never forget the day ＿＿ we worked together.A.which B.when C.in which D.where （选B,为什么?）两道题差不多,为什么选的答案不一样?