Millions of aircraft take off around the world every year. The skies they fly in seem limitless—miles of empty space. But, with the number of flights increasing each year, this emptiness no longer exists. Researchers in the world of aviation（航空）are worried about the increasing pressure on pilots and ground controllers. And increasing collisions, occurring at or near an airport, have called attention to the need for more aids（辅助设备）to aviation control. People who travel the skies are not certain about air safety. A great deal of money is spent on new and bigger aircraft and airports to deal with the vast increase in passengers travelling by air. Only a small percentage of this money is spent on navigation（导航）and other aids. Actually, suitable electronic equipment has long existed, and many companies market safety aids designed to make it safer for aircraft to take off, fly any distance, and land, whatever the weather. Yet, there are two problems to be solved. The first is to get governments, airlines and airport officials to agree to basic levels of safety aids. The second problem is to find a way of meeting these basic requirements. But no matter how well the equipment works, operators of the equipment still play an important role. Communications between pilots and ground controllers are extremely important to air safety. It is worth pointing out that the mishearing or misunderstanding of instructions in English and the use of another language, in an international conversation, have led to two recent aircraft accidents. A new type of instrument（仪器）called FLIGHTWATCH would help pilots prevent airport collisions. It would be particularly helpful near airports.The increasing number of flights leads to the fact that ________. There is uncertainty about air safety because ________. The underlined word “collisions” probably means ________. It can be inferred from the passage that ________. flying is no longer limited in the sky,there is no empty space for aids to aviation control,piloting and controlling planes is getting more difficult,the pressure on the ground becomes greater,flying is no longer limited in the sky,there is no empty space for aids to aviation control,piloting and controlling planes is getting more difficult,the pressure on the ground becomes greater,planes become bigger for the increasing number of passengers,money spent on electronic equipment is far from enough,suitable electronic equipment hasn’t been invented yet,it is dangerous for planes to take off or land,planes become bigger for the increasing number of passengers,money spent on electronic equipment is far from enough,suitable electronic equipment hasn’t been invented yet,it is dangerous for planes to take off or land,accidents in which two planes hit each other,misunderstandings between pilots and ground controllers,quarrels among passengers ,breakdowns of new types of instrument,accidents in which two planes hit each other,misunderstandings between pilots and ground controllers,quarrels among passengers ,breakdowns of new types of instrument,governments and officials have paid great attention to air safety,there should be more companies to sell new safety aids,English should be used in an international conversation,understanding between pilots and ground controllers should be improved,governments and officials have paid great attention to air safety,there should be more companies to sell new safety aids,English should be used in an international conversation,understanding between pilots and ground controllers should be improved