规则15 用肯定形式表述[rule-15]

做出明确的断言。避免平淡、苍白、犹豫、不置可否的语言。把not这个词用作否定或对照的手段，绝不要用作回避的手段。

• 误：He was not very often on time.
• 正：He usually came late.

• 误：She did not think that studying Latin was a sensible way to use one's time.
• 正：She thought the study of Latin a waste of time.

• 误：The Taming of the Shrew is rather weak in spots. Shakespeare does not portray Katharine as a very admirable character, nor does Bianca remain long in memory as an important character in Shakespeare's works.
• 正：The women in The Taming of the Shrew are unattractive. Katharine is disagreeable, Bianca insignificant.

最后一个例子在修改之前，既含混又是否定的。因此，修改后的版本其实只是对写作者意图的一种猜测。

三个例子都显示了not这个词固有的弱点。读者无论有意还是无意，都不满足于只被告知不是什么；读者希望被告知是什么。因此，一般说来，即使是否定，也最好用肯定形式来表达。

• not honest — dishonest
• not important — trifling
• did not remember — forgot
• did not pay any attention to — ignored
• did not have much confidence in — distrusted

把否定与肯定对置，能形成更强的结构。

Not charity, but simple justice. Not that I loved Caesar less, but that I loved Rome more. Ask not what your country can do for you—ask what you can do for your country.

除not之外的否定词通常很有力。

Her loveliness I never knew / Until she smiled on me.

用不必要的助动词或条件词加以限定的陈述，听起来优柔寡断。

• 误：If you would let us know the time of your arrival, we would be happy to arrange your transportation from the airport.
• 正：If you will let us know the time of your arrival, we shall be happy to arrange your transportation from the airport.

• 误：Applicants can make a good impression by being neat and punctual.
• 正：Applicants will make a good impression if they are neat and punctual.

• 误：Plath may be ranked among those modern poets who died young.
• 正：Plath was one of those modern poets who died young.

如果你每一个句子都带有疑问，你的写作就会缺乏权威。把助动词would、should、could、may、might和can留到真正存在不确定性的场合使用。