Don't be joking. It's time to____________ your business. 

 Learn some useful skills, or, I’m afraid, you would ______ nothing in society. 

 To ______ the other players, the athlete ________ a lot of difficulties in his training.

---How did it _________ that all the flowers died ? ---I had forgotten to water them.

She was so angry that she _____ something at him, but she finally controlled herself.．