37. According to the way in which a thought is put before a
listener or reader, sentences may be of three kinds:--

(1) Declarative, which puts the thought in the form of a declaration
or assertion. This is the most common one.

(2) Interrogative, which puts the thought in a question.

(3) Imperative, which expresses command, entreaty, or request.

Any one of these may be put in the form of an exclamation, but the
sentence would still be declarative, interrogative, or imperative;
hence, _according to form_, there are only the three kinds of
sentences already named.

Examples of these three kinds are, declarative, "Old year, you must
not die!" interrogative, "Hath he not always treasures, always
friends?" imperative, "Come to the bridal chamber, Death!"

CLASSIFICATION ACCORDING TO NUMBER OF STATEMENTS.

SIMPLE SENTENCES.

[Sidenote: _Division according to number of statements._]

338. But the division of sentences most necessary to analysis is the
division, not according to the form in which a thought is put, but
according to how many statements there are.

The one we shall consider first is the simple sentence.

[Sidenote: _Definition._]

339. A simple sentence is one which contains a single statement,
question, or command: for example, "The quality of mercy is not
strained;" "What wouldst thou do, old man?" "Be thou familiar, but by
no means vulgar."

340. Every sentence must contain two parts,--a subject and a
predicate.

[Sidenote: _Definition: Predicate._]

The predicate of a sentence is a verb or verb phrase which says
something about the subject.

In order to get a correct definition of the subject, let us examine
two specimen sentences:--

1. But now all is to be changed.

2. A rare old plant is the ivy green.

In the first sentence we find the subject by placing the word _what_
before the predicate,--_What_ is to be changed? Answer, _all_.
Consequently, we say _all_ is the subject of the sentence.

But if we try this with the second sentence, we have some
trouble,--_What_ is the ivy green? Answer, _a rare old plant_. But we
cannot help seeing that an assertion is made, not of _a rare old
plant_, but about _the ivy green_; and the real subject is the latter.
Sentences are frequently in this inverted order, especially in poetry;
and our definition must be the following, to suit all cases:--

[Sidenote: _Subject._]

The subject is that which answers the question _who_