Mary said she(would have ) a birthday party the next Monday.
玛利说她下星期一举行一个生日晚会.
加油!不明白再问!但答案是was having解析说be doing表将来，这里考查的是过去将来时。 我不能理解也可以呀因为主句是一般过去时SAID ,从句要用相应的过去时态，故用 was having