单选题 Please translate the following sentence from English into Chinese(考试题型5,英译汉:此处单选为示例,考试中需自己写出翻译内容)(备注:考试题型4为阅读理解) The objectives of the air traffic services shall be to prevent collisions between aircraft, prevent collisions between aircraft on the maneuvering area and obstructions on that area, expedite and maintain an orderly flow of air traffic, provide advice and information useful for the safe and efficient conduct of flights, notify appropriate organizations regarding aircraft in need of search and rescue aid, and assist such organizations as required