1.This destructor would have to be called specifically before unsetting the parent class reference.
这种解构器必须在解除父类引用之前进行调用。
2.The first step is to make sure that the user is logged out by unsetting the relevant session variables.
第一步，确保用户是通过取消相关会话变量来进行注销的。
3.Torture-test an application by setting and unsetting a bunch of values of different types for keys on the command line.
通过在命令行上为键设置和取消设置各种不同类型的值，对应用程序进行严格的测试。
4.A type of mechanism commonly used in the setting and unsetting of downhole tools and equipment such as packers.
在坐封和释放井下工具和设备（如封隔器）中普遍使用的一种机构。