Books are the greatest friends. (Positive)

A compound sentence consists of two or more independent clauses, each of which can stand alone as a complete sentence. These independent clauses are typically joined by a coordinating conjunction (such as and, but, or, so, for, nor, yet) or a semicolon.

In the given sentence, "In order to acquire knowledge, we should read books," the phrase "In order to acquire knowledge" indicates purpose. To convert this into a compound sentence, we need to create two independent clauses. One clause states the action ("We should read books"), and the other states the result or ability derived from that action ("we can acquire knowledge").

By using the coordinating conjunction "and," we connect these two clauses, forming a grammatically correct compound sentence: "We should read books, and we can acquire knowledge."

To change a sentence from active voice to passive voice, the object of the active sentence becomes the subject of the passive sentence. The verb form also changes, typically using a form of 'to be' followed by the past participle of the main verb. In this sentence, 'Books' is the subject and 'us' is the object in the active voice. Therefore, 'us' changes to 'We' as the new subject in the passive voice. The simple present tense verb 'introduce' changes to 'are introduced' in the passive form, and the original subject 'books' becomes the agent, preceded by 'by'.

The books of great writers contain noble thoughts and great ideas. (Complex) = The books of great writers which contain Nobel thoughts and great ideas.