_____ you ever _____ to Nanjing? —Yes, I _____ there last year.

Several students were working _____the difficult math problem after class. [ ]

Do you think if Tom the work well?—I think he will if he his best.

His report was so exciting that it wasinterrupted by applause（掌声）.

____ the help of the teacher, Tom has made rapid progress ____ his studies. [ ]