以历史性字母组合hw -开头的英语单词不是太多了，然而使用频率很高的单词which, when, what, why以及where (where和这组词有点不同)仍然不允许我们忘记它们的存在。

English words with the historical initial hw - are not too many; yet the highly frequent which, when, what, why, and where (who stands somewhat apart from this group) do not allow us to forget them.

youdao