letter key的用法和樣例：
例句
- After it opens, pressing the appropriate letter key executes the function.
助記符模式打開(kāi)以后，按下適當的字母鍵就可以執行相應的功能。 - To compact data by combining parts of the data, for example, to transform a two-word alphabetic key into a one-word numeric key by adding the numeric equivalents of the letters.
通過(guò)將數據的某些部分進(jìn)行組合來(lái)壓縮數據，例如，通過(guò)將一些字母的數字等值相加，可把兩個(gè)字長(cháng)的字母鍵詞變換為一個(gè)字長(cháng)的數字鍵詞。
