[译] 这道微分方程和那道一样复杂。
[误] This differential equation is so complicated as that one.

[正] This differential equation is as complicated as that one.
[注] 连词 as...as 可以带 not, 也可以不带 not, 如: Smith is as diligent as John. 史密斯和约翰一样勤奋。也可以说: Smith is not as old as John is. 史密斯年龄没有约翰大。so...as 只带 not, 不用于肯定句，如: Jane is not so clever as her elder sister. 珍妮不及她姐姐聪明。