+285.+ The adverbs _how_, _when_, _where_, _why_, _whither_, _whence_,
etc., are used in asking questions, and when they are used in this way
they are called interrogative adverbs. For example:
_How_ did it happen?
_Where_ are you going?
_Whence_ came he?
_When_ did he come?
_Why_ did you do it?
_Whither_ are you going?
These adverbs, _how_, _when_, _where_, _why_, _whence_ and _whither_,
are used in these sentences to modify the verbs and ask the questions
concerning the _time_ or _place_ or _manner_ of action expressed in the
verb.
_How_ may also be used as an interrogative adverb modifying an adjective
or another adverb. For example:
How late did he stay?
How large is the house?
In the first sentence, the adverb _how_ modifies the adverb _late_, and
introduces the question. In the second sentence _how_ modifies the
adjective _large_ and introduces the question.