「刪除冗字」是William Strunk和E.B. White在其有關增進文筆的經典作品《The Elements of Style》中提出的其中一個基本創作原則。銘記這個建議可以為正在準備繳交發表科學論文的您，提供極大的幫助，而要消除文句中的冗字，進而讓「每一個字都有意義」有好幾種方式，我們可以從填補句型「It is known that」開始。
雖然填補句型也是好文筆的一環，但是使用填補句型常常會造成過長的句子，有時甚至會混淆讀者。請參考以下範例：
This result indicated that the N and O atoms of the ligand were coordinated to the metal ion. It is known that the coordination mode of a carboxylate ion to a metal can be estimated from…
有些讀者可能會在看到It is known that的時候停下來，一時把虛主詞it誤解為metal iron，因為它是離it最近的單數名詞。為避免此誤解以及去除不必要的單字，句子可以改為：
This result indicated that the N and O atoms of the ligand were coordinated to the metal ion. The coordination mode of a carboxylate ion to a metal can be estimated from…
有關虛主詞It常見謬義，列舉了以下幾個範例。
原句：
It is known that most analogs with this general formula exhibit cross-resistance.
修改A：
Most analogs with this general formula are known to exhibit cross-resistance.
修改B：
Most analogs with this general formula exhibit cross-resistance.
原句：
It is known that the two species are anionic and that they form an ion pair with an organic cation.
修改後：
The two species are anionic, and they form an ion pair with an organic cation.
原句：
It is known that Henry’s law constants have temperature dependence.
修改後：
Henry’s law constants depend on temperature.
原句：
It is known that the translational diffusion of the molecule is much faster than that predicted by the Stokes–Einstein equation.
修改後：
The translational diffusion of the molecule is much faster than that predicted by the Stokes–Einstein equation.
原句：
It is generally thought that its therapeutic effect is triggered by…
修改後：
Its therapeutic effect is generally thought to be triggered by…
原句：
It should be noted that the former method has an advantage over the latter.
修改後：
Note that the former method has an advantage over the latter.
或是
The former method has an advantage over the latter.
原句：
It is also reported that diffusion is exceptionally slow.
修改A：
Diffusion is reported to be exceptionally slow.
修改B：
Diffusion is exceptionally slow.
當您因為期刊字數要求，必須縮短摘要篇幅的時候，這些簡單的修改會非常有幫助。因此，您可以在繳交論文之前快速瀏覽文章中的it is，並做出適當修改，特別是緊跟在單數名詞後面的it。
參考資料：
Strunk, William, and E.B. White, The Elements of Style, 3d ed. (New York: Macmillan, 1979), p. 23.
For some excellent examples of the usefulness of expletive constructions, see what Joseph M. Williams refers to as “it-shifts” in Style: Toward Clarity and Grace (Chicago: University of Chicago Press, 1990), p. 72.
For a more-extensive discussion of this problem, and other problems with “it is,” see Bryan A. Garner, Garner’s Modern American Usage, 3d. ed. (Oxford: Oxford University Press, 2009), p. 484.
