51. Adjective clauses may be introduced (1) by the pronouns who, which, and that, or (2) by adverbs like where, whence, whither, when.
Adverbial clauses may be introduced (1) by the adverbs where, whither, whence, when, while, before, after, until, how, as, or (2) by the conjunctions because, though, although, if, that (in order that, so that), lest, etc.
Note. The use of phrases and clauses as parts of speech increases enormously the richness and power of language. Though English has a huge stock of words, it cannot provide a separate noun or adjective or adverb for every idea. By grouping words, however, in phrases and clauses we, in effect, make a great variety of new nouns, adjectives, and adverbs, each precisely fitted to the needs of the moment in the expression of thought.
SUMMARY OF DEFINITIONS
The Sentence
1. Language is thought expressed in words.
2. To express thought words are combined into sentences.
3. A sentence is a group of words which expresses a complete thought.
4. Sentences may be declarative, interrogative, imperative, or exclamatory.
(1) A declarative sentence declares or asserts something as a fact.