Conversion of active voice to passive voice follows certain rules. However, not all sentences can be converted into passive voice. We will discuss here all such types of sentences which cannot be converted into passive voice.

Sentences of the following four tenses cannot be changed into passive voice:

1. Present Perfect Continuous Tense
2. Past Perfect Continuous Tense
3. Future Perfect Continuous Tense
4. Future Continuous Tense

Sentences containing intransitive verbs cannot be converted into passive voice. There are two types of verbs:

Transitive Verbs
Intransitive Verbs

A transitive verb is a verb that requires an object in the sentence to convey complete meaning. For instance, buy is a transitive verb. See the following example:

He bought _____.
He bought a book.

In the example above, without an object, the verb buy does not convey complete meaning. A transitive verb must have an object in the sentence, such as in He bought a book or He bought a chair.

On the other hand, intransitive verbs do not require an object and can convey complete meaning on their own. For example, laugh, sleep, and run are intransitive verbs:

He laughs.
She is sleeping.
They are running.

The sentence having intransitive verbs cannot be changed into passive voice.The key requirement for forming a passive sentence is the presence of an object. If this condition is not met, conversion into the passive voice is not possible. Therefore, sentences with intransitive verbs cannot be converted into passive voice.

Examples sentences with intransive verbs:.

He is laughing.
He has gone.
She is sleeping.
The baby is crying.
The patient is coughing.
They are dancing.
The guests have arrived.
He was standing.
He died.
It is raining.
They disappeared.
The kids were smiling.

Remember, in some cases, additional words may appear after an intransitive verb. These words are not objects, but they may confuse the reader into assuming as if they function as objects. However, such sentences still cannot be converted into passive voice.

For example, go is an intransitive verb and may be used as follows:

 He goes to school.

In this sentence, school is not an object; rather, it functions as an adverb of place. Therefore, the sentence cannot be converted into passive voice. Adverbs of place and time are commonly used after intransitive verbs to provide additional information, but they should not be mistaken for objects.

Additional Examples

Sleep, sit, reach, die, go, disappear, and talk are common intransitive verbs. Consider the following examples, where additional words follow the verbs but do not function as objects:

He is sleeping in the bed.
She is sitting on a table.
He reached his home.
She died from cancer.
They went to the library.
He disappeared from the scene.
We talked all the night.