The best way to improve your vocabulary is through reading.请问through在这里是什么词性?是prep还是adv?为什么?

The best way to improve your vocabulary is through reading.请问through在这里是什么词性?是prep还是adv?为什么?
The best way to improve your vocabulary is through reading.
请问through在这里是什么词性?是prep还是adv?为什么?

The best way to improve your vocabulary is through reading.请问through在这里是什么词性?是prep还是adv?为什么?
介词,相当于 by
副词是修饰 动词的,这里不和is构成修饰关系.

prep介词，后面接名词或者动名词

是介词，通过的意思
通过阅读是提高词汇量的最好办法。
副词一般修饰动词后置。

through在这里是介词
介词后面要接名次/动名词
The best way to improve your vocabulary is through reading.
阅读是最好的增加词汇方式
through reading 通过阅读

prep