+376.+ The adjective clauses which we have been studying so far have
been introduced by relative pronouns. Adjective clauses may also be
introduced by conjunctions, such as, _where_, _when_, _whence_, or
_why_. As, for example:
Antwerp is the place where a terrible battle was fought.
No man knows the hour when opportunity will be his.
Each group has a different reason why this world-war was precipitated.
Note in these sentences the clauses, _where a terrible battle was
fought_, _when opportunity will be his_, _why this world-war was
precipitated_, are all adjective clauses modifying the nouns _place_,
_hour_ and _reason_, and are introduced by the conjunctions _where_,
_when_, and _why_. These are adjective clauses because they modify, by
either limiting or describing, the nouns with which they are used. You
will note that we could omit the nouns in the first two of these
sentences and these clauses would become noun clauses, for they would be
used in the place of a noun. As, for example:
Antwerp is where a terrible battle was fought.
No man knows when opportunity will be his.
+377.+ We determine whether a clause is an adjective or an adverb or a
noun clause just as we determine whether a word is an adjective, adverb
or noun, by the work which it does in a sentence. Noun clauses are used
in the place of a noun; adverb clauses modify verbs, adjectives, and
adverbs; adjective clauses modify nouns and pronouns.