Mr Brown was going away for a week. Before he left, he said to his son, "if anyone asks for me, you can tell him that your father has been out for doing something, and will be back in a week, then be sure to ask him to sit down for a cup of tea."

 "OK, Dad," said his son. But he was afraid his son couldn't remember this, he wrote these words down on a piece of paper and gave it to him. His son put it into his small pocket, took it out and looked at it now and then.

 Four days passed, but no one came to see his father. The boy thought that there was no man to come and that the piece of paper was of no more use for him, so he burnt it that evening.

 The next afternoon, someone knocked at the door. The boy opened it. A man was standing at the door and said, "Where is your father?" The boy put his hand into his pocket at once and looked for the piece of paper. He could not find it. He suddenly remembered he had burnt it, so he shouted, "No more."

 The man was very surprised. He asked, "No more? I met your father last week. When did it happen?"

 "Burnt yesterday evening."

Mr Brown told his son that _____.

A. he would be away from home for four days

B. he would be back in seven days

C. he would be back in a month

D. he liked a cup of tea

Mr Brown wrote the words down on ________.

A. the wall B. the door

C. a piece of paper D. his son's pocket

A man came to visit the boy's father on ________.

A. the second day B. the third day C. the fourth day D. the fifth day

What was burnt? ___________.

The piece of paper B. Mr Smith C. The visitor D. The boy

Scientists studying the impact of climate change on the Arctic need to consider ways to reduce their own carbon footprints(碳排放量), says Ryan Brook, a researcher who regularly flies north to study the health of caribous(驯鹿).He calls on scientists to show leadership by examining and sharing ways to reduce the impact of working in polar regions.

“The importance of the research is not at question here. It is important to our understanding of and adapting to climate change. But we need to think about better approaches,” says Brook.

“This is an issue for all scientists, though polar researchers often travel particularly long distances using commercial air travel. We also rely extensively on small aircraft, icebreakers, and snowmobiles, all of which produce large amounts of carbon.”

Brook studies the health of caribou herds in Nunavut and Northwest Territories. He works with northern wildlife managers. This work typically takes him north five or six times per year and when he calculated his own carbon footprint, he was not happy with the result.

“My research footprints are about the same as the annual footprints of an average Toronto resident. Basically, I have two footprints — my own personal life, which is moderate, and my research footprint.”

Climate scientists can rightly argue that Arctic research is a specialized field and the community of scientists who travel north is relatively small. Even if all scientists working in the north reduced their carbon emissions, it would not make a big impact on the global scale. For Brook, it’s the option that matters.

There are ways researchers can reduce the amount of carbon they use. Some helicopters use less fuel than others. Solar and wind power are alternatives to gas-fired generators. And while carbon offsets(抵消) don’t reduce the amount of carbon emitted, they are an easy first step.

“There aren’t necessarily any easy answers, but we need to start talking about it,” says Brook. “This is particularly important for the next generation of scientists being trained and I hope to see them become leaders in this issue.”

What did Brook find when he calculated his own carbon footprints?

A. His carbon footprints are more than the annual footprints of a Toronto resident.

B. His personal life footprints are more than the annual footprints of a Toronto resident.

C. His research footprints are about the same as his personal life footprints.

D. His personal life footprints are more than his research footprints.

Brook’s opinion is challenged by the statement that       .

A. arctic research is very important

B. the Arctic is a special environment

C. the footprints of Arctic scientists are small

D. Brook’s situation is a common phenomenon

We can infer from the last paragraph that         .

A. we should take actions immediately instead of just talking

B. it’s easy to start talking about the problem of carbon emissions

C. it’s necessary now to pay attention to the problem of research footprints

D. the next generation of scientists are more interested in research footprints

What’s the main idea of the text?

A. The importance of arctic research is not at question.

B. Climate change becomes worse because of arctic research.

C. Brook suggests ways of reducing the use of carbon.

D. Scientists must look at their own carbon footprints.

My parents live in a small village. They always keep candles in the house __________ there is a power cut.

A. if   B. unless   C. in case   D. so that