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Simple, Complex, and Compound Sentences:

Read the following sentences:

1)     A goal properly set is halfway reached.

2)     Thousands of candles can be lighted from a single candle, and the life of the candle will not be shortened.

3)     To every complex problem there is an easy answer; and it is wrong!

4)     Time is the best teacher; but unfortunately it kills all its students!

5)     He who fails to prepare, prepares to fail.

You can see that the first sentence has only one subject and one predicate. Such a sentence is called a Simple Sentence.

The second and third sentence consists of two parts:

Thousands of candles can be lighted from a single candle, and the life of the candle will not be shortened.

a)     Thousands of candles can be lighted from a single candle.

b)    The life of the candle will not be shortened.

To every complex problem there is an easy answer; and it is wrong!

a)     To every complex problem there is an easy answer.

b)    It is wrong.

Both these parts are joined by the Coordinating Conjunction “and.” Each of the two parts have a subject and a predicate of its own, and therefore each part is a sentence which is part of a larger sentence. Hence each part is a clause. Furthermore each part makes good sense by itself therefore are independent of the other, hence both are Principal or Main Clauses. Thus a sentence formed using Principal or Main Clauses is called Compound Sentence.

The fourth and fifth sentence consists of two parts also:

Time is the best teacher; but unfortunately it kills all its students!

a)     Time is the best teacher.

b)    But unfortunately it kills all its students!

He who fails to prepare, prepares to fail.

a)     He prepares to fail.

b)    Who fails to prepare.

 Here too both parts have a subject and predicate, and form a part of a large sentence, hence each part is a clause. But upon closer examination you would notice that the clause “a” of each sentence make good sense by itself and forms a complete sentence, thus are called the Main Clause or Principal Clause. But clauses “b" of each sentence cannot stand by itself and make good sense, thus they are dependent on the Main or Principal Clause. Hence are called Dependent or Subordinate Clause.

Thus a sentence that consists of one Main Clause and one or more Dependent or Subordinate Clause is called Complex Sentence.