By the time you come back, your aunt ______ for Nanjing to attend a meeting.  

—Is there a fog in the evening ?—There________be . I’ll make a phone call to find it out .

I ______ sooner but I didn’t know that they were waiting for me.

It’s required that the students___ mobile phones in their school, so seldom ____ them using one.   

Kunming is called “Spring City”, but it _____ snow in winter.