"字要写的漂亮" 的英文表达可以是 "the characters should be written beautifully" 或 "the writing should be beautiful." 这句话的来源可能源于对于书写美观的重视。

下面是一些例句：

这封信的字要写的漂亮。(The writing in this letter should be beautiful.)
这篇文章的字要写的漂亮。(The writing in this article should be beautiful.)
这幅画的字要写的漂亮。(The writing on this painting should be beautiful.)

在英文中，"beautiful" 还可以用来形容书写或印刷的质量，意思是 "优美的，美观的"。例如：

这本书的印刷质量非常好，字写得很漂亮。(The printing quapty of this book is very good, the writing is beautiful.)
这份文件的字写得很漂亮，看起来很整洁。(The writing in this document is beautiful, it looks neat.)