not so... as/not as... as

不管语法书上怎么说,现在的事实是:这两种用法在一般情况下是可以互换使用的。例如：

1. He's not as naughty as he was. (CGEL) 他不像以前那么调皮了。

2. He's not so naughty as he was. (CGEL) 他不像从前那么调皮了。

3. John is $\$left\{\begin{aligned}as & polite \\ not & \left\{\begin{aligned}so \\ as\end{aligned}\right\}polite\end{aligned}\right\} as Bob (is). $\$left\{\begin{aligned}约翰和鲍勃一样有礼貌。\\ 约翰不如鲍勃有礼貌。\end{aligned}\right.

4. John $\$left\{\begin{array}{l} behaves as politely \\ does not behave \left\{\begin{array}{l} so \\ as \end{array}\right\} politely \end{array}\right\} as Bob (does). $\$left\{\begin{array}{l} 约翰的行为和鲍勃一样有礼貌。 \\ 约翰的行为不如鲍勃有礼貌。 \end{array}\right.

5. Soames is not as/not so suitable for the job as me. (LEG) 索姆斯不如我更适合这项工作。

(参见 as...as $^{3}$ )