Machines such as trebuchets were the heavy artillery of the pre-gunpowder era.

而抛石机这类机器，则是火药时代的重型火炮。

A trebuchet consists of a long beam attached to a pivot rod on a heavy frame.

抛石机是由一个带转轴的长连接在底座上构的。

But along this stabilized shoreline here where we have riprap or large boulders, we have corals that have settled and are thriving.

但在这条稳定的海岸线上有抛石或巨大的巨石，有珊瑚定居并在这里长。

We include  rock riprap or other armoring on the upstream face so that waves and swift water in the reservoir  can't erode the vulnerable embankment.

我们在上游面添加岩石抛石或其他防护层，这样水库中的波浪和湍急的水流就不会侵蚀脆弱的路堤。