The agent with by is omitted in passive voice when it is implicit.

I was doing an exercise in which I had to change the sentence

He kept me waiting

into the active voice. According to me the active voice is

I was kept waiting by him

but in the solution by him is omitted. Him can not be omitted because it specifies a particular person. It may be an opportunity also like

I was kept waiting by this opportunity.

What I want to ask is why by him should be omitted.

2 Answers 2


You have things wrong.

He kept me waiting

is already active voice

I was kept waiting (by him)

is already passive voice.

"By him" is optional from a grammar point of view, but it adds information to the meaning.

  • Ya I know that unknowingly I wrote opposite of what was there in the book. Sorry for that. But what about assessment???? Mar 7, 2019 at 10:31
  • the "assessment" was about an older version of the answer
    – virolino
    Mar 7, 2019 at 10:37
  • I have deleted my earlier comments, as they have been addressed. :) Mar 7, 2019 at 15:16

I was kept waiting by him.

The part "by him" doesn't add any information or value to the sentence which is in the passive voice. I'm sure you know that as you wrote it correctly in your question title.

And the action in the passive voice should become known when adding the "by ___" section which won't be achieved if you add "by him" as the person would still be anonymous. That's why it is better been omitted.

But if it was a person's name, for example. Then you would be right in your explanation for the need for its existence.

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