To help the driver keep track of the instances, the system sends a driver instance handle with each driver message after the instance has been created.

为了能够使得驱动程序跟踪这些实例，系统会在实例创建完成后在每个驱动消息中带有一个驱动实例句柄。

youdao

Sending a message to an object that does not handle that message is an error. However, before announcing the error, the runtime system gives the receiving object a second chance to handle the message.

当一个对象不能正常及时处理发送过来的消息时会导致异常，runtime系统在发生异常之前提供了第二次机会处理消息的机会。

youdao

Many firms handle the problem by ensuring that a recorded message automatically plays when this situation arises but Ofcom rules decree that this system - known as "abandoned calls" - should not be used in more than 3% of all calls made in any 24-hour period.

BBC: NEWS | UK | 'Silent calls' warning welcomed