Answer:

To determine whether the sentence "I know him" is in the active or passive voice, we need to understand the basic concepts of active and passive voices.

Active Voice:
In the active voice, the subject of the sentence performs the action. The subject is the doer of the action, and the verb in the sentence directly relates to the subject.

Passive Voice:
In the passive voice, the subject of the sentence receives the action. The subject becomes the receiver of the action, and the verb is modified to show this relationship.

Now, let's analyze the given sentence "I know him" to determine its voice.

Subject: "I"
Verb: "know"
Object: "him"

Since the subject "I" is performing the action of knowing, the sentence is in the active voice. Therefore, the sentence "I know him" is in the active voice.

Summary:
- The sentence "I know him" is in the active voice.
- The subject "I" is the doer of the action.
- The verb "know" directly relates to the subject.
- The object "him" receives the action of being known by the subject.

By understanding the concepts of active and passive voices and analyzing the given sentence, we can conclude that the sentence is in the active voice.