【单选题】Before a new type of airplane goes into service, every part of it is tested again and again. But there are two tests that are more important than all the others. The first is called the 'tank test'. A...
【单选题】听力原文: Before a new plane goes into service, every part of it is tested again and again. But there are two tests that are more important than ail the others. In the first test, a modern airliner must f...