彼之砒霜，汝之蜜糖。
原文链接：https://blogs.msdn.microsoft.com/oldnewthing/20040329-00/?p=40003
You may have noticed that Windows doesn’t use Ctrl+Alt as a keyboard shortcut anywhere. (Or at least it shouldn’t.) If a chorded modifier is needed, it’s usually Ctrl+Shift.
你可能会注意到Windows没有在任何地方使用Ctrl+Alt作为键盘快捷键。（或者至少不应该这么做）（译注：Ctrl+Alt+Del不算……）如果需要用到双联的修饰键，通常都会是Ctrl+Shift。
That’s because Ctrl+Alt has special meaning on many keyboards. The combination Ctrl+Alt is also known as AltGr, and it acts as an alternate shift key. For example, consider the German keyboard layout. Notice that there are three keyboard shift states (Normal, Shift, and AltGr), whereas on U.S. keyboards there are only two (Normal and Shift). For example, to type the @ character on a German keyboard, you would type AltGr+Q = Ctrl+Alt+Q. (Some languages, like Swedish, have a fourth state: Shift+AltGr. And then of course, there’s the Japanese keyboard…)
这是因为Ctrl+Alt在很多键盘布局上有特殊的用途。Ctrl+Alt的按键组合也被称作AltGr，作为一个特殊的换挡键使用。例如，观察一个德语键盘布局，会发现其包含三种换挡模式（正常模式、Shift档及AltGr档），而美国英语键盘布局上只有两种（正常模式和Shift档）。例如，要在德语键盘上输入@字符，需要按下AltGr+Q，也就等于按下Ctrl+Alt+Q。（某些语言的键盘布局，例如瑞典语，还有第四种换挡模式：Shift+AltGr，当然了，还有日语键盘……）
Most international keyboards remap the right-hand Alt key to act as AltGr, so instead of the finger-contorting Ctrl+Alt+Q, you can usually type RAlt+Q.
大多数国际键盘布局将右手Alt键映射为AltGr，这样你就不用拧着手指去按Ctrl+Alt+Q了，只要按右Alt+Q就可以了。（译注：我怎么觉得Ctrl+Alt+Q更好按一点……）
(For reference, here are diagrams of several other keyboard layouts, courtesy of my bubble-blowing friend, Nadine Kano.)
（作为参考，这里有另外的几种键盘布局，感谢我的好朋友Nadine Kano的提供。）（译注：原文链接已失效）
Sometimes a program accidentally uses Ctrl+Alt as a shortcut modifier and they get bug reports like, “Every time I type the letter ‘đ’, the program thinks I want to start a mailmerge.”
有时候，某些应用程序不小心设计了Ctrl+Alt开头的键盘快捷键，然后他们就会收到这样的bug反馈：『每次我想录入字母đ的时候，程序都会以为我想启动邮件合并。』
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