每一种操作都具有前提和后期条件，并且它们能够提出例外。

Each of these operations can have preconditions and post-conditions, and they can raise exceptions.

youdao

当然，这三种操作符(单引号、双引号和反撇号)都有合法的用途，但是与英语中的例外一样，记住和掌握这些细微差异很令人头疼。

Certainly, all three operators-the single, double, and back quotation marks-serve a valid purpose, but like exceptions in English, memorizing and mastering the variations can be maddening.

youdao

一个例外是在执行mount命令时指定了direct _ io选项(这于read操作的情况类似)。

An exception to this is when the direct_io mount option is specified (as in the read operation).

youdao