change to passive voice

1. they promise us higher wages

2. this is the third time they have written to us about this

1.  Higher wages were promised to us by them.
2. They have written the third time to us about this.

what is voice

 vn

1) Higher wages were promised to us.

like plz

Higher wages were promised to us by them.

They have written this to us third time this year.

higher wages were promised to us.

and second one is they have been to us third time this year.

higher wages were promised to us.

and second one is they have been to us third time this year.