And a position is defendable where you won't lose the game if you play optimal moves.

一个位置是可防守，前提是如果你下出最佳着法，就不会输掉比赛。

The Bithynian town of Prusa had fallen to them in 1326, giving them a defendable base from which to reduce the remaining Roman outposts.

比提普鲁萨镇于1326年落入他们之手，这为他们提供了一个可防守基地， 从而进一步削弱了马残余据点。

Many eminent men have found a sort of gloomy comfort in this idea, but science has now opened up possibilities for the future which makes this theory less defendable.

许多知名人士在这个想法中找到了一种令人沮丧安慰，现在为未来开辟了可能性，这使得这个理论不那么可靠。

We're in an oil-based economy. And we should have the type of energy security which allows us to have defendable supply lines and not pay for our oil to those who want to do harm to the United States.

我们处于一个以石油为基础经济中。我们应该拥有那种能够保障供应线路安全并使我们不必向那些想对美国造成伤害人购买石油能量安全。