说明当至少定义了一个关键字时，您可以接受特殊的类。

Indicate that you can accept a particular class when there is at least one keyword defined.

youdao

但是当我拿起魔笔，写下一个字时，我发现那个字非常丑。

But when I picked the pen up and wrote down a character, I found it very ugly.

youdao

原来上面的小字是写着：“当你能看到上面的字时，回来找我做检查。”

In very tiny letters, the stamp said, "When you can read this, come back and see me."

youdao

I guess when you put markets on it that doesn't sound like public finance but, even so, it could.

我想当你用到“市场“二字时,听起来跟公共财政就是两码事了,尽管如此，两者仍有关联。

耶鲁公开课 - 金融市场课程节选

So when you see the word book,the mechanical thing they're actually talking about is a scroll.

所以当你看到书这个字时,他们实质上说的是卷轴。

耶鲁公开课 - 新约课程节选

This is a search box that every Chinese is familiar with, but when you look at people's needs, people are typing all kinds of queries in this box. For example... "A great MP3", "Where can I find a girlfriend in Beijing?"

这是一个中国人都很熟悉的搜索框，但是当关注到人们的需求时就会发现，人们在框中输入,各种关键字。,比如，“听起来让人觉得开心的MP3“,“北京哪里能找到女朋友结婚？“

斯坦福公开课 - 百度CEO李彦宏演讲：全球最大搜索引擎的发展课程节选