Why use the passive and not the active?

Why use the passive and not the active?

The question we must ask is what is the sentence about?

The structure- active or passive - depends on how the sentence starts.

Sometimes the passive is the more natural choice. Think of the situations where you would read the following and you will see why the passive is the obvious choice:

1. Children must be carried.
2. Outdoor shoes must not be worn in the gym.
3. These gates will be locked at 8pm daily.
4. Hard hats must be worn at all times.

No. 1 is a sign in the London Underground at the top and bottom of escalators. It
has more impact than If you have a child with you, please carry him or her.

No. 2 is a sign in a school outside the gymnasium. It is more direct than You mustn't
wear your outdoor shoes in the gym.

No. 3 is a sign on the gates of a park warning people to be out of the park before
the gates are locked. Warning signs are always as short as possible.

No. 4 is a common sign on building sites. Again, it is an important safety sign and
needs to be as short as possible. You must wear a hard hat at all times does not have
the impact or authority of the passive.