从and you didn't (事实上你昨天也没去）可见didn't need to come 是对的（你写错了多了个need)
didn't need to do sth 表示“过去没必要做什么”（事实上也没做） 如果事实上已经做了,就得说“needn't have done"了
请及时采纳,不懂继续问( 天天在线 ）