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

而机这类机器，则是火药时代的重型火炮。

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

但在这条定的海岸线上有巨大的巨，有珊瑚定居并在这里茁壮成长。

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

机是由一个带转轴的长梁连接在底座上构成的。

Behind me is a replica of a small siege  engine called a perrier.

我身后是一个叫做机的小型围攻器械的复制品。