可能你在其它网站注册时或者在网上买票时就填过验证码了。

You have likely seen this before when signing up for websites or buying tickets online.

youdao

UI - patterns是另外一个顶级用户界面库，收集展示了一些改进过的设计模型，比如验证码、帐户注册、导航标签等。

UI-patterns is another top-notch User Interface library that collects and showcases reoccurring design patterns such as Captchas, Account Registrations, and Navigation Tabs.

youdao

于是，我要做的就是，当注册页面出现时，在邮件地址“@yourdomain.com” 前面加上一个数字以及输入验证码，然后点击“现在注册”按钮。

So all I had to do when the signup screen loaded was enter a number before the @ sign in email, enter the captcha, and click signup.

youdao