The end address is invalid. Enter a valid address.

结束地址无效。请输入一个有效的地址。

youdao

The address pool is empty. Add a valid address pool.

地址池为空。请添加一个有效的地址池。

youdao

The start address is invalid. Enter a valid address.

起始地址无效。请输入一个有效的地址。

youdao

But when you start writing programs, especially when we get to web-based stuff where you want -- to check the user's input -- is it valid, is it an email address, -- and all these different scenarios -- it's actually often useful to be able to just enumerate them or rattle them off using this switching construct instead.

但是当你看是写程序时，特别是当我们,使用基于网络的东西，你想要,检查用户的输入-,它是合法的吗？它是不是一个电子邮箱地址？,所有的这些场景-,实际上它常常是有用的，当你用枚举结构列举它们,或者用它来快速地来说出它们。

哈佛公开课 - 计算机科学课程节选

Users are then responsible for registering a single account with a valid email address, credit card details along with a billing address (alternatively, a valid Paypal ID).

FORBES: European Courts Rule In Favor Of Consumers Reselling Downloaded Games

That means you have to register with Forbes.com using a valid email address.

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They also failed to follow state requirements to include a valid return address.

BBC: NEWS | Technology | California wins anti-spam case