E 级和 A 级空域的区别在于，在 A 级空域，所有操作都需遵照仪表飞行规则，飞行员必须要有仪表等级，也就是说，要有操作航空仪表方面的技术和执照。
The difference between Class E and A airspace is that in Class A, all operations are IFR, and pilots must be instrument-rated, that is, skilled and licensed in aircraft instrumentation.
数字技术也使人们更容易协调他们的活动，而不用诉诸等级制度。
Digital technology also makes it easier for people to co-ordinate their activities without resorting to hierarchy.
因此一个复杂的问题就是，何时为第三世界而开发这本身就是在制造一个技术等级。
Therefore, the tricky question when you’re inventing for the developing world is creating the right level of technology.
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