I _____not thank you too much for your help. 

There is no _________ that the Chinese people will present to the world a successful, splendid and unforgettable exposition（博览会）.

—Are you still working in that company, Mary?—No, it is ten months ____ I worked there．

You should spend more time ______ the lessons.

I’m sorry I can’t help ___________ the flowers, because I’m busy preparing for the singing competition _____________ tomorrow.