By the year 1889, there were just 541 bison in the whole of North America. A. leaving alive B. to leave alive C. to be left alive D. left alive 题目和参考答案——青夏教育精英家教网—

One night, as Diaz stepped off the train and onto a nearly empty platform, a teenage boy approached and pulled out a knife.
“He wanted my money, so I just gave him my wallet and told him, ‘Here you go ’” Diaz says.
As the teen began to walk away, Diaz told him, “Hey, wait a minute. You forgot something. If you’re going to be robbing people for the rest of the night, you might as well take my coat to keep you warm.”
The robber looked at him puzzled, saying, “Why are you doing this?”
Diaz replied, “If you’re willing to risk your freedom for a few dollars, then you must really need the money. I mean, all I wanted to do was get dinner and if you really want to join me…..”
Diaz says he and the teen went into a diner and sat in a booth.
“The manager comes by, the dishwashers come by, the waiters come by to say hi,” Diaz says.
The kid said, “You know everybody here. Do you own this place?”
“No, I just eat here a lot,” Dias said. “But you’re even nice to the dishwasher,” he said.
Diaz replied, “Well, haven’t you been taught you should be nice to everybody?”
“Yea, but I didn’t think people actually behaved that way,” the teen said.
When the bill arrived, Diaz said, “You’re going to have to pay for this bill because you have my money and I can’t pay for this. So if you give me my wallet back, I’ll gladly treat you.”
The teen returned it immediately. “I gave him $20…. I figure maybe it’ll help him.” Diaz says he asked for something in return--- the teen’s knife--- “and he gave it to me.”
Afterwards, when Diaz told his mother what happened, she said, “You’re the type of kid that if someone asked you for the time, you gave them your watch.”
“I figure, you know, if you treat people right, you can only hope that they treat you right. It’s as simple as it gets in this complicated world.”
【小题1】What did Diaz do to the teen?

A．He gave the teen a new wallet	B．He treated the teen to dinner
C．He gave his coat to the teen	D．He taught the teen a lesson

【小题2】From the passage we can infer that the boy _______.

A．expressed his gratitude for Diaz’s kindness

B．gave up the idea of robbing in the end

C．wasn’t taught how to be nice to everybody

D．gave the knife to Diaz in return for his forgiveness

【小题3】For what Diaz did, his mother showed an attitude of _______.

【小题4】By telling the story of Diaz, the author intends to tell us ______.

A．to keep calm in danger	B．not to go out alone at night
C．to treat others kindly	D．not to harm others on purpose

Astronomers have captured(捕获) the first direct image of a planet being born.

Adam Kraus, of the University of Hawaii’s Institute for Astronomy, said the planet is being formed out of dust and gas circling a 2-million-yea-old star about 450 light years from Earth.

The planet itself, based on scientific models of how planets form, is believed to have started taking shape about 50,000 to 100,000 years ago.

Called LkCa 15b, it’s the youngest planet ever observed. The previous record holder was about five times older.

Kraus and his colleague, Michael Ireland from Macquarie University and the Australian Astronomical Observatory, used Keck telescopes on Mauna Kea(a volcano on the island of Hawaii, US) to find the planet. Kraus presented the discovery Wednesday at NASA’s Goddard Space Flight Center in Maryland.

Observing planets while they’re forming can help scientists answer questions like weather planets form early in the life of a star or later, and whether they form relatively close to stars or father away.

Planets can change orbits(轨道) after forming, so it’s difficult to answer such questions by studying older planets.

“These very basic questions of when and where are best answered when you can actually see the planet forming, as the process is happening right now,” Kraus said.

Scientists hadn’t been able to see such young planets before because the stars they’re circling around outshine(光亮强过) them. Kraus and Ireland used two techniques to overcome this problem.

One method, which is also used by other astronomers, was to change the shape of the telescope mirrors to remove light distortion(扭曲) created by the Earth’s atmosphere. The other method they used, which was unique, was to put masks with several holes over most of the telescope mirrors. The combination of these techniques allowed the astronomers to obtain high-quality images that let them see the planet next to the bright star.

The star LkCa 15—the planet is named after its star—was the team’s second target. They immediately knew they were seeing something new, so they plan to gather more data on the star.

1.The research on younger planets helps scientists _____________.

A. study why planets change orbits after forming

B. understand how planets move around their stars

C. answer questions about the age of stars and planets

D. know the relationship between planets and their stars

2.Why are young planets like LkCa 15b hard to discover?

A. Their stars are brighter than them.. B. They are very far from the earth.

C. They are generally too small. D. They rarely form.

3.According to the text, Kraus and Ireland _____________.

A. have been working in the same university

B. observed the planet on a volcano in Hawaii

C. used two new methods in the observation

D. cut holes in the mirrors when observing

4.Which of the following would be the best title for the text?

A. Youngest planet seen as it’s forming.

B. Planet 450 light years away discovered.

C. World’s first direct image of a planet taken.

D. New technique helps discover young planets.