What is the difference between active and passive infinitives in grammar?

In grammar, the difference between active and passive infinitives lies in the way the action of the verb is expressed.

Active infinitives are formed by using the base form of the verb, also known as the infinitive form, without any additional words. They represent the action of the verb as being performed by the subject of the sentence. For example, in the sentence "She loves to sing," the active infinitive is "to sing," and it indicates that the subject "she" is the one performing the action of singing.

On the other hand, passive infinitives are formed by using the auxiliary verb "to be" followed by the past participle form of the main verb. They represent the action of the verb as being done to the subject of the sentence. For example, in the sentence "The book needs to be read," the passive infinitive is "to be read," and it suggests that the action of reading is being done to the subject "the book."

The distinction between active and passive infinitives becomes more apparent when considering the subject and object of a sentence. In active infinitives, the subject is the doer of the action, while in passive infinitives, the subject is the receiver of the action. For instance, in the active infinitive sentence "He wants to eat the cake," the subject "he" is the one who wants to perform the action of eating, and the object "the cake" is the receiver of the action. In contrast, in the passive infinitive sentence "The cake needs to be eaten," the subject "the cake" is the receiver of the action of being eaten, and the doer of the action is not explicitly mentioned.

Overall, the difference between active and passive infinitives lies in the perspective of the action: active infinitives emphasize the subject as the doer of the action, while passive infinitives highlight the subject as the receiver of the action.