The verb ending -mus denotes first person plural verbs in Latin.
You make a conclusion based on what you read or whatever.
As soon as their able to make full on sentences, parents will usually start transitioning them into using honorifics so they can properly talk to older folks.
I believe that it is: borrowed from other signs.
Hope this helps!
Answer:
the spanish word for pager is buscapersonas
Explanation: