English crossword clues are exercises in riddling—one of my favourites was “golden parent” in three letters, answer “mum.”

（英文的填字游戏就像猜谜——我最喜欢的一条是golden parent，让猜三个字母的单词，答案是mum）。

youdao

In all existing life forms, the four "letters" of the genetic code, called nucleotides, are read in triplets, so that every three nucleotides encode a single amino acid.

在所有现有的生命形式中的四个“字母”的遗传密码，即核苷酸，是以三个为单位读取的，每三个核苷酸编码成为一个单独的氨基酸。

youdao

Therefore, gifts, letters, and guests will often arrive at your home in groups of three.

因此，礼物、信件和客人常常会成三出现在你的家。

youdao

So to type the word "wish, " I'd find the first three letters in squares, selecting each of them.

WSJ: From QWERTY to Quirky: New Ways to Type on Glass

Jenkins worked at the Press while earning three letters in golf at Texas Christian University from 1950 to 1952.

WSJ: Dan Jenkins, Finding the Humor in Golf | Golf Journal by John Paul Newport

The council received three letters in support of the plans, which said the turbines would bring jobs, contribute towards carbon reduction, generate funds for the local economy through a community benefit fund and were a "sufficient distance" from homes.

BBC: Llanllwni