[单项选择]When the end of the world comes, we’ll know what to blame. Scientists have found compelling evidence that the Sun has a baby brother, a dark star whose eccentric orbit is responsible for periodically showering the Earth with comets and meteorites.
The dark star—named Nemesis by astronomers—is thought to be a brown dwarf that spins round the Sun in an orbit so large that it is measured in light years, the distance light travels in a year, equivalent to about 6,000 billion miles.
The research suggests that, every 26m years, the star’s eccentric orbit brings it within one light year of the solar system. There it causes havoc in the Oort Cloud, a huge region surrounding the solar system that contains billions of bits of cosmic rubble left over from the formation of planets.
Of the millions of rocks it throws out of orbit at each visit, some hurtle earthwards—and have several times nearly wiped out life on Earth.
Astronomers have long wondered if the Sun has a smaller pa
A. It’s bright. B. It’s not very big. C. It’s not a planet. D. It’s huge.

[单项选择]When the end of the world comes, we’ll know what to blame. Scientists have found compelling evidence that the Sun has a baby brother, a dark star whose eccentric orbit is responsible for periodically showering the Earth with comets and meteorites.
The dark star—named Nemesis by astronomers—is thought to be a brown dwarf that spins round the Sun in an orbit so large that it is measured in light years, the distance light travels in a year, equivalent to about 6,000 billion miles.
The research suggests that, every 26m years, the star’s eccentric orbit brings it within one light year of the solar system. There it causes havoc in the Oort Cloud, a huge region surrounding the solar system that contains billions of bits of cosmic rubble left over from the formation of planets.
Of the millions of rocks it throws out of orbit at each visit, some hurtle earthwards—and have several times nearly wiped out life on Earth.
Astronomers have long wondered if the Sun has a smaller pa
A. It contributes to showering of comets on the earth.
B. It is a smaller partner of the Sun.
C. It has a large orbit.
D. It contains bits of cosmic rubble.

[单项选择]What should we know while claiming scientific knowledge of "human nature"
A. The variations in the human physique.
B. The similarities in human physique.
C. How people from different cultures solve their problems.
D. What all human beings have in common.

[单项选择]What do we know about Mike
A. His sister will leave for Canada.
B. His sister will leave China.
C. His sister will leave Canada.

[单项选择]What do we know about John
A. He likes talking about his job.
B. He intends to have a pay raise.
C. He means to change to another job.
D. He is persistent in his own job.

[单项选择]What do we know about Brown
A. He called the woman last weekend.
B. He is the man’s classmate.
C. He doesn’t live in this city.

[单项选择]What can we know about Montreal
A. Montreal is the third largest city in the world.
B. Montreal is the capital city of Quebec province.
C. Most of the road sings in Montreal are in English.
D. People in Montreal mostly speak French.

[单项选择]What do we know about Bill
A. He is thoughtful.
B. He is forgetful.
C. He is careless.
D. He is helpful.

[单项选择]What do we know about Susan
A. She learned Spanish in America.
B. She doesn’t know Spanish.
C. She improved her Spanish in Mexico.
D. She knew Spanish before going to Mexico.