doesn't depend on how you got from A to B.

跟你从 A 点到 B 点的路径无关
Even more interesting is that

更有趣的是
all the fundamental forces that we know --

所有我们所知道的基本力
gravity, electrostatics,

引力静电力
even the strong force, weak force,

甚至是强作用力弱作用力
every force that we know to the extent it can be described by a force --

所有我们已知范围内可以描述的力
happens to be conservative.

恰好都是保守力
So, it's not that we are hung up

所以我们并不是仅限于
on some rather exceptional case;

一些例外的情形
nature is kind enough that

自然很善良
all the forces are conservative.

让所有的力都是保守的
Now, friction is a little tricky.

摩擦力情况有点棘手