【简答题】Fortunately, however, ___1____men made tools of stone, especially __2____, because this is easier to ___3__ than other kinds. They may also have used wood and skins, but these have ___4___ away. Stone...
【单选题】There was an earthquake on the coast yesterday. Fortunately, there was no loss of life. However, because of the danger of collapsing sea walls, it was essential that the area _______ evacuated quickly...