perfect continuousgrade 9b students are studying in the library

(+) they have grade 9b students are studiying in the library
(-) they have not grade 9b students are studiying in the library
(?) haven't they grade 9b students are studiying in the library
mohon maaf ya sebisanya

=> Answer :
(+) Grade 9b students have been studying in the library.
(-) Grade 9b students haven't been studying in the library.
(?) Have grade 9b students been studying in the library ?


Maaf jika salah. Semoga membantu ^_^