4.过去，城市里常有很多鸟儿歌唱。 There used to be a lot of birds singing in the city. 5.他们从没听说过这件事。 They have never heard of this thing. 6.当你离开房间的时候要关灯 Turn off the lights when you leave the room. 导航页导航页 4.过去,城市里常有很多鸟儿歌唱。 There ________ ______ ______a lot of birds singing in the city. 5.他们从没听说过这件事。 They have never ______ ____this thing. 6.当你离开房间的时候要关灯 _________ ________the lights when you leave the room. used to be heard of Turn off