This is the 11971st most frequent Turkish word.
girmişlerdir
"They have entered."
The word 'girmişlerdir' is used in the past perfect tense to indicate that students went into the classroom.
Öğrenciler sınıfa girmişlerdir.
The students have entered the classroom.
Here, 'girmişlerdir' suggests a completed action of entering the room and is plural to reflect multiple subjects.
Gruptaki arkadaşlar toplantı salonuna girmişlerdir.
The friends in the group have entered the meeting room.
In this sentence, the verb 'girmişlerdir' is in the indicative mood and specifies a past completed action related to place entry during the nighttime.