two level

基本解释

From this we see both two level quoting (>>) and one level quoting (>).
在这个例子中，我们看到了两层引用（>>）和一层引用（>）。
That is because it does not include two Level 2 process areas, which cover essential best practices for project implementation.
这是由于它没有包括2级的两个过程领域，而它们包含了项目实现中基本的最佳实践。
If the two level curves are tangent to each other that means they have the same tangent line. That means that the normal vectors should be parallel. Let me maybe draw a picture here.
如果两个等高线相切，说明它们的切线相同,也就是说他们的法向量应该平行,我再在这里画个图。

The city is more than two thousand meters above sea level, near the southern Rocky Mountains in northern New Mexico.
There is no machine yet that can recognize faces or understand sentences at the level of a two-year-old human.
至今还没有任何机器,能够做到面孔识别,或是理解两岁儿童能够轻易理解的句子
耶鲁公开课 - 心理学导论课程节选
On one level, there are things like companies that have two . different classes of stock that are economically identical.
一方面，我们有这样的例子，有的公司拥有两种,不同类别的股票，他们在经济意义上是相同的。
耶鲁公开课 - 金融市场课程节选