Welcome,Donia
Passive voice
I am not going to tell you when we normally use
passive voice or active voice.this is not needed
the national exam usually requires some rules
to apply
passive voice simply means

ut the direct object
in the place of the subject respecting
the tense of the verb
let us have some examples
They speak english everywhere
English is spoken everywhere
They spoke english everywhere
English was spoken everywhere
They have spoken english everywhere
English has been spoken everywhere
They are writing a report
A report is being written
They will write a report tomorrow
A report will be written tomorrow
They were making progress
Progress was being made
They could write the report
The report could be written
They might have read the letter
The letter might have been read
GOOD LUCK