PASSIVE VOICE
~ Present tense
He is known as the leader of this group.
~ Past tense
He was known as the leader of this group.
ACTIVE VOICE
~ Present tense
We (or "people, they, everyone," etc) know him as the leader of this group.
~ Past tense
We (or "people, they, everyone," etc) knew him as the leader of this group.
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In the active voice, the person who "knows him" is the subject of the sentence.
In the passive voice, the person who "is known" is used as the subject.
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One trick to tell if a sentence is in the passive voice is to add the words "by zombies." If the sentence still works, it is in the passive voice,
EXAMPLES:
> He is known by zombies as the leader of this group. OK - PASSIVE
> We know him by zombies as the leader of this group. NOT OK. ACTIVE
> Everyone knew him as the leader of this group by zombies. ACTIVE
> He was known as the leader of this group by zombies. OK - PASSIVE
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Most of the time, a passive sentence has
1) Some form of the verb TO BE
2) The use (stated or implied) of the expression BY (whomever)
EXAMPLES:
> He WAS hated BY everyone who knew him. PASSIVE
> Everyone who knew him hated him. ACTIVE
> The show WAS watched attentively BY the enchanted audience. PASSIVE
> The enchanted audience watched the show attentively. ACTIVE
> Birds ARE hunted BY cats and other predators. PASSIVE
> Cats and other predators hunt birds. ACTIVE