A first grader can write the person's name. By fourth grade children should be able to write the time of the call and the reason for the call as well as the name of the caller.
还不太会写的孩子可以只写下名字，大一些的孩子应能写下接电话的时间，打电话的原因和打电话人的姓名。
2
Here I've used the new keyword enum, given the enum a name, and specified the allowed values. Grade then becomes an enumerated type, which you can use in a manner shown in Listing 3.
在这里，我使用了新的关键字enum，为enum提供了一个名称，并指定了允许的值。
3
Sam was the one who hit me with a basketball at recess in second grade. And Sam is the one who still calls me the annoying name of Arizoni Macarconi!