1. Using the lowercase letter in general should be avoided, because it is easily mistaken for the number 1. 一般情况下，我们应该避免使用小写字母，因为它很容易被误当作数字1。
2. Your Password Must contain at least one number, at least one English uppercase character, and one English lowercase character. 你的密码必须至少包含一个数字，至少一个大写字母，至少一个小写字母。
3. Small caps. You could guess it already from the name, small caps are small capitals. Capitals which have the same height as lowercase characters. 你可能看名字就猜出来了，小型大写就是小号的大写字母。和小写字母一样高度的大写字母。
英英解释
n.
1. the characters that were once kept in bottom half of a compositor's type case
2. relating to small (not capitalized) letters that were kept in the lower half of a compositor's type
