I mean, again, 99% of the vector fields that we see in this class are defined everywhere so that's not an urgent concern, but still.

再次强调在，课堂上我们看到的99%的向量场，都是处处有定义的，就不必很担心了，但是还得注意。

youdao

Data: An object; a generic reference that is carried along to listeners; often a collection class (such as a Vector or Hashtable) or a customized data object.

data：一个对象；传递给侦听程序的一般引用；常常是一个集合类(如vector或Hashtable)或一个定制的数据对象。

youdao

Recall that the methods of the Vector class are nearly all synchronized.

回想一下，vector类的方法几乎都是同步的。

youdao