I helped my mum clean the rooms.为什么help用过去式clean却不用呢?

I helped my mum clean the rooms.为什么help用过去式clean却不用呢? 动词过去式后的动词怎么弄?如：I helped him clean the room,为什么clean不用变? I helped him clean the room为什么clean 是原形；那My teacher asked me i often help my mother clean the house.为什么clean用原型? I often help my mother clean the room clean为什么不能用cleans? 照理来 I often help my mother clean the room clean为什么不能用cleans?照理来说 I helped my mother clean the room yesterday.还是I helped my mo I always heip my mum clean the with a_______ He often helps my mum to clean the house on Sunday.为什么用to cl I often help my mother clean the room.这句话中clean前的to可以用吗? 用go,clean的正确形式填空 _____ you ______ the room ,Mum?Can I help y i often help my father (clean)the car on weekends