Scientists say that banana trees may disappear(消失) from the world       banana cancer.

 “Mr. Zhu, you’d better          too much meat . You’re already over weight .” said the doctor .

Our neighbor Mr. Smith used to_______ money but he never gave it back.

 Now more and more people prefer _____ to_____ in order to reduce the air pollution.

His father hoped         a doctor when he was a child .