The rural workforce has been flowing in to the cities ever since the open door policy was adopted.
自从改革开放政策实施以来,农付劳动力正不断流向城市。
Our own warm atmosphere and the heat generated by the telescope would make it impossible to detect objects as small as planets.
地球周围温暖的大气层和望远镜散出的热量使得我们根本不可能找到比行星更小的物体。