I will never forgot these days when(in which) we played together；and I will never forgot these days we spent together.为什么第一句用 when(in which)？第二句不行？1）play是不及物动词不及物动词 vi. 1.玩耍;游戏;戏弄;玩弄[(+with)]Children like to playwe played together所以，从句是完整的句子，应该填关系副词或是介词+关系代词we played together in these days。2）而spent是及物动词，及物动词 vt. 花(时间、精力)[(+on)][O4]They spent three month touring Europe. 他们花了三个月时间周游欧洲。所以，第二句从句缺少宾语，填that/which 都可，而这两个在做宾语时可以省略哪里不明白的再问！！