Question

The call had to be booked twenty four hours in advance at that time.(change the voice)​

Answer 1

The given passive voice sentence can be changed into active voice sentence as shown and explained below:

People had to book the call twenty four hours in advance at that time.

Explanation

This is a subject implied case. A subject implied sentence in active-passive voice is a sentence that is passive but the subject is missing. While converting it into active we have to provide the subject from our side. This sentence is already passive. So we will provide the subject ‘People’ from our side.

Passive: O + had to + be + V3.

Active: S + had to + V1 + O.

Answer 2

Answer:

People had to book that call twenty four hours in advance at that time.