Names should be formed from the 26 upper and lower case letters (A .. Z, a .. z), the 10 digits (0 .. 9), and _ (underbar).

变量名应由26个大小写字母(A..Z,a..z),10个数字(0..9),和_(下划线)组成。

youdao

They have to distinguish between words in upper and lower-case letters or even harder, they had to count the number of syllables in different words.

他们必须区分大写和小写的单词，或者更难的是，他们必须数出不同单词的音节数。

youdao

Note: To make sure, that you can find all occurrences of the specified terms, and because these terms are not known by the underlying dictionary, write the terms in all lower-case letters.

注意：要确定您可以找到指定术语的所有匹配项，并且由于这些术语对于底层字典是未知的，需要全部使用小写字母写入术语。

youdao

Now, once you know each of those, you can now do 25 more upper case letters and 25 more lower case letters then there are some other stuff like punctuation and things you see on the keyboard.

一旦你知道两者中的任何一个，你就知道了另外25个,大写字母和小写字母,标点和在键盘上的,各种符号也有ASCII码。

哈佛公开课 - 计算机科学课程节选

Passwords for all accounts should be 10 characters long and include upper and lower case letters, numbers, and special characters.

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She writes it confidently and proudly, lower case letters and all.

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One of their biggest decisions, which caused upset among conservative commentators at the time, was to opt for a combination of upper and lower case letters.

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