In each of the following simple sentences either the subject or the predicate or both are compound:—

COMPOUND SENTENCES

451. If we attach another simple sentence to that in [§ 450], the result is a compound sentence.

The polar bear | lives in the Arctic regions, || but || it | sometimes reaches temperate latitudes.

This is manifestly a compound sentence, for it consists of two coördinate clauses, joined by the conjunction but ([§ 46]).

The framework of the second clause consists of the subject it and the simple predicate reaches. To make the complete predicate, the verb reaches takes not only a modifier (the adverb sometimes), but a complement,—the direct object latitudes, which completes the meaning of the verb. This noun is itself modified by the adjective temperate. Both clauses are simple, for each contains but one subject and one predicate.

452. Obviously, almost any number of simple sentences may be joined (with or without conjunctions) to make one compound sentence.

The quiet August noon has come;
A slumberous silence fills the sky;
The fields are still, the woods are dumb,
In glassy sleep the waters lie.—Bryant.