You shouldn't knock at the door.简单一些的句子有没I heard a knock at the door. 在黑暗中他撞了一样东西。 I hear someone knock at the door. 我听见有人敲门了。 Do you hear the knock at the door ?? 幸福常常敲我们的门。 There was a knock at the door . 有人在门上敲了三下。 I was surprised by a knock at the door . 有人敲门使我吃了一惊。 Please knock at the door before entering. 进来之前请先敲门。 When I was taking a nap , a student must knock at the door. 正当我午睡时，偏偏一个学生在这个时候来敲门。 The dog 's ears perked up when hearing a knock at the door . 狗听见有人在敲门，竖起了耳朵。