这是一篇GMAT里面说美国经济模式的文章。主要是在批评的他们经济模式的不灵活，改革困难。
But
Americans imagined a condition in which speculators, self-makers, runners
are always using the new opportunities given by our land. These economic
leaders (front-runners) would thus be mainly agents of change.
The nonstarters were considered the ones who wanted stability, a strong
referee to give them some position in the race, a regulative hand （这里主要指什么）to calm manic
speculation; an authority that can call things to a halt, begin things again
from 【compensatorily staggered “starting lines.”】这里什么意思？
“Reform” in America has been sterile because it can imagine nochange except through the extension of this metaphor of a race, wider inclusionof competitors, “apiece of the action,” as it were, for the disenfranchised. 这一段可以帮我全部解释一下吗？
But Americans imagined a condition 【in which speculators, self-makers, runners are always using the new opportunities given by our land.定语从句，修饰condition】
但是美国人设想出了一种情况，在这种情况下，投机者，自营商，跑路党通常会利用这片土地所给予的新机遇。
These economic leaders (front-runners) would thus be mainly agents of change.
这些经济领袖（领跑者）会因此而成为变革的主要动力。
......
祥见附件。供参考。