所有语言都有两种基本的用法——正式用法和通俗用法。

All languages have two general levels of usage—a formal level and an informal level.

youdao

它的正式用法包括将 USN 与 null 进行比较，或在两个 USN 值之间进行比较，以得出它们的小于、等于和大于关系。

The actual official use that you can make of it is comparing it against null or comparing two USNs for less than, greater than, or equal values.

youdao

但是在正式写作中，标准用法仍然是使用whom。

But "whom" is still standard in formal writing.

youdao