I will never forgot these days when(in which) we played together；and I will never forgot these days we spent together.為什么第一句用 when(in which)？第二句不行？1）play是不及物動詞不及物動詞 vi. 1.玩耍;游戲;戲弄;玩弄[(+with)]Children like to playwe played together所以，從句是完整的句子，應該填關系副詞或是介詞+關系代詞we played together in these days。2）而spent是及物動詞，及物動詞 vt. 花(時間、精力)[(+on)][O4]They spent three month touring Europe. 他們花了三個月時間周游歐洲。所以，第二句從句缺少賓語，填that/which 都可，而這兩個在做賓語時可以省略哪里不明白的再問??！