You call the pst office
"has arrived" is the verb phrase in "has my brother arrived yet".
"Has arrived" is the verb phrase in the given sentence "Has your brother arrived yet".
In the sentence, "yet" is a coordinating conjunction.
(A+) the sentence is (or should be) "Has my brother arrived yet?" the verb phrase is "has arrived"
"Mail" is a mass noun, so it adopts the grammar of a singular noun ("The mail is here." "Has the mail arrived yet?"), although it cannot be pluralised (1 mail, 2 mails) or combined with an indefinite article (a mail). Other examples of mass nouns are "luggage" and "advice".
In the sentence, "yet" is a coordinating conjunction.
arrived
The verb is has arrived.
Keldeo is an event Pokemon whose event hasn't arrived yet.
He has his invitation but he has not yet arrived.
He has his invitation but he has not yet arrived.
Correlating Conjunction