It can also save time, if it turns out (as it often does) that the only thing done with the node-set is to test whether it is empty, or to get the value of its first element.
它还可以节省时间，如果对于节点集的唯一操作就是测试它是否是空的(通常是这种情况)，或者对它的第一个元素进行赋值。
You can test for them explicitly or rely on PHP to return a default empty value when you reference them.
您可以显式地对它们进行检测，或在您引用它们时让PHP返回缺省的空值。
Groundless and empty theory can never stand the test of practice.
毫无实践的虚无理论，根本经不起验证.自谓迷徒，实乃自以为是看破时间万物的一个傻孩子。
You can do this either by recording an interaction with the server you're testing or by creating an empty test and building it from scratch.
您可以通过记录与您测试的服务器之间的交互或是创建一个空的测试并通过手工添加测试元素来构建它。
You can also create an empty database unit test and add code later to test other types of database objects.
您也可以建立一个空的资料库单元测试，稍后再新增程序码以测试其他类型的资料库专案。
Friday will examine, but my in the mind allows however gets empty to fall of, don't know to review good have no, can test how much divide attention in also has been have no a bottom.
星期五就要考试了，但我的心里任然空落落的，不知复习好了没有，能考多少分心里也一直没有一个底。我真想考一个好一点的分数，但毕竟是要通过努力才能达成的，好好学习吧！
Friday will examine, but my in the mind allows however gets empty to fall of, don't know to review good have no, can test how much divide attention in also has been have no a bottom.
星期五就要考试了，但我的心里任然空落落的，不知复习好了没有，能考多少分心里也一直没有一个底。我真想考一个好一点的分数，但毕竟是要通过努力才能达成的，好好学习吧！
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