It was practical books about fortifications, hydraulics, artillery, navigation, and shipbuilding.

而是实际的书籍,比如有关防御工事的,水力学,炮术,航海和造船的

耶鲁公开课 - 欧洲文明课程节选

The heavy artillery in the orchestra is what?

管弦乐团中的重炮是什么

耶鲁公开课 - 聆听音乐课程节选

So, held back here the heavy artillery.

那么,藏在后面的是重炮

耶鲁公开课 - 聆听音乐课程节选