句意填空If you listen to the teacher-------in your class,you'

句意填空If you listen to the teacher_______in your class,you'll get good grades.为什么?涉及什么语法吗?
2.what languages_________in that country?Chinese and English.A.are speking B.are spoken C.speak,理由
3.I don't know________.Because he has to look after his mother.A.why is he leaving B.whether he is leaving C.why he is leaving