______ has an internal clock that regulates the beating of our hearts, and the ______ of our breathing.
| A．Mankind; step | B．Human; pace | C．Human being; step | D．Man; pace |
The teacher praised me for ________ progress I'd made, which was ________ great encouragement to me.
| A．the; / | B．the; a |
| C．/; a | D．/; / |
As ________ birthplace of Huaxia civilization, Xi'an is ________ city with a long history and abundant cultural relics.
| A．the; a | B．a; a |
| C．/; a | D．the; / |
University is ________ most worthwhile time of discovery and learning, and it is also ________ very enjoyable and valuable experience for every one of us.
| A．a; a | B．the; / |
| C．/; a | D．a; the |
The patient's family has expressed their ________ to the press in letters for the money raised.
| A．purpose | B．apologies |
| C．gratitude | D．sympathy |
It was a difficult job for him.He had tried everything but it made little ________.
| A．use | B．good |
| C．difference | D．result |