Airline booking system, passive voice

Look at this flow chart on a flight booking system:

Active voice- the object receives the action of the verb.
(You use this "voice" most often)

Active

subject

verb

object

Programmers

use

HTML.

Passive voice- the subject receives the action of the verb. (You use this "voice" less often)

Passive

subject

verb

object

HTML

is used

by programmers.

The object of the active verb becomes the subject of the passive verb:

subject

verb

object

Active

Everybody

uses

computers.

Passive

Computers

are used

by everybody.

Decide whether the following are active or passive voice:

1) First, the flight number is entered by the user.

2) After, the number of seats available is checked.

3) The user books the tickets online.

4) The tickets are booked online.

5) The main computer updates the flight information.

6) The booking is confirmed.