+248.+ Qualifying adjectives are also called _descriptive_ adjectives
because they describe the noun. They answer the questions _which_ and
_what kind_.
You remember we found in the beginning of our study of English, that
words were grouped into classes according to the work which they do in
the sentence, not according to the form of the word itself. For
instance, we have already found that some words, without changing their
form, may be used either as a noun or as a verb. Take the word _oil_,
for instance. I may say, _I oil the engine_. Here I have used the word
_oil_ as a verb telling what I do. But I may say, _The oil is gone_.
Here I have used the word _oil_ as a noun, subject of the sentence. The
part of speech to which a word belongs in the English language, always
depends upon the work which it does in the sentence.
+1.+ So we have nouns which are used as descriptive adjectives, for
example the word _oil_, which we have found we can use either as a noun
or a verb, may also be used as an adjective. For example; I may say,
_the oil tank_. Here I have used the word _oil_ as a descriptive
adjective modifying the word _tank_. So also we may say, _the oak tree_,
_the stone curb_, _the earth wall_. In these expressions _oak_, _stone_
and _earth_ are nouns used as descriptive adjectives.
+2.+ We have descriptive adjectives derived from proper nouns, as
French, English, American. These are called proper adjectives; and since
all proper nouns must begin with a capital letter, these proper
adjectives, also, should always begin with a capital letter.
+3.+ We have also descriptive adjectives derived from verbs as _active_,
_talkative_, _movable_, _desirable_, derived by the addition of suffixes
to the verbs _act_, _talk_, _move_ and _desire_.