n.航空；飞机制造业
At that time aviation was still in its infancy. 当时航空仍在萌芽阶段。
Jets are a new development in aviation. 喷气式飞机是航空事业上的一个新成就。
In old China,there was hardly any machine- building industry,to say nothing of automobile and aviation industries. 旧中国几乎没有机器制造业，更不用说汽车制造业和飞机制造业了。
