定义名为“学号”的属性，该属性的类型为“string”，该属性在XML中必须出现，下面正确的选项是（ ）。 A: <!attribute name="学号" type="string" use="required" /> B: <attribute name="学号" type="string" use="prohibited" /> C: <attribute name="学号" type="string" use="required" /> D: <attribute name="学号" type="string" use="optional" />

Which is optional on the envelop?

Optional是一种集合类型

In CNC panel, there are optional function switches.

Which of the following parts of business correspondence is optional?

Word中插入数学公式的方法是（）。 A: "插入"→"形状"→"公式" B: "开发工具"→"公式" C: "插入"→"公式"→"插入新公式" D: "引用"→"插入"→"公式"

Which one of the following is the optional part of a business letter?

定义并初始化一个用于存放我们国家的四个直辖市的数组cityName，四个直辖市为：北京，上海，天津，重庆. 正确的是_________ A: String[] cityName=new String[4]{"北京","上海","天津","重庆"}; B: String[] cityName=new String[]{"北京","上海","天津","重庆"}; C: String[] cityName={"北京","上海","天津","重庆"}; D: String cityName = new String[4] { "北京", "上海", "天津", "重庆" };

A verb phrase must contain a verb， but other elements are optional。 （ ）

已知有一个名为names的空列表,如何向其中添加old_driver,rain,jack,shanshan,peiqi,black_girl 元素？ A: names.append("old_driver","rain","jack","shanshan","peiqi","black_girl") B: names.extend("old_driver","rain","jack","shanshan","peiqi","black_girl") C: names.insert("old_driver","rain","jack","shanshan","peiqi","black_girl") D: names.extend(["old_driver","rain","jack","shanshan","peiqi","black_girl"])