+400.+ Every expression of a complete thought is a sentence. A sentence
is the unit in language. Words are the material out of which we build
our sentences, so we have been studying the various parts of speech that
are used in sentence building. Now we are ready to use these parts of
speech in the building of sentences. We have found that there are eight
parts of speech, though the interjection, which is termed the eighth
part of speech, is not in reality a part of the sentence; but is a
complete, independent construction. So in your sentences all of the many
hundreds of words which we use can be grouped into seven divisions;
_nouns_, _pronouns_, _adjectives_, _verbs_, _adverbs_, _prepositions_
and _conjunctions_.
+401.+ You remember in our first lesson we found that there were just
three kinds of sentences. The _assertive_, the _interrogative_ and the
_imperative_; or in other words, sentences which state a _fact_, ask a
_question_ or give a _command_. We also found that these three kinds of
sentences could all be expressed in _exclamatory_ form.