[单项选择]Cosmic rays of various kinds come through the air from outer space, but enormous quantities of radiation from the sun are ______ off.
A. avoided
B. excluded
C. screened
D. separated

[单项选择]Cosmic rays of various kinds come through the air from outer space, but enormous quantities of radiation from the sun are ______ off.
A. avoided
B. excluded
C. screened
D. separated

[单项选择]Without air protection, the sun's rays______.


A. will become very cold
B. will do good to human beings
C. will become hot
D. will do harm to human beings

[单项选择]I come into ______with all kinds of people in my work.
A. contact
B. concern
C. complacence
D. compliance

[单项选择]X-rays are also called Rontgen rays ______ the discoverer who first put them to use.
A. in case of
B. in view of
C. in place of
D. in honor of

[单项选择]Conservative scientists who deny that cosmic gulfs can ever be crossed will ______.
A. laugh at the very idea of flight
B. learn a lesson as they did ten years ago
C. find space travel beyond their reach
D. oppose the fundamental scientific laws

[单项选择]Confronted with the new groups of cosmic reality, many educated men ______.
A. become ignorant savages again
B. find the "time barrier" unbearable
C. will not combine solar and stellar space
D. cannot adapt to the abrupt change of scale

[单项选择]Conventional X-rays mainly show the difference between _________.


A. bone and air
B. liver and pancreas
C. muscle and other body
D. heart and lungs

[单项选择]According to the passage, as the corona rays reach the planets, they become ______.


A. hotter
B. clearer
C. thinner
D. stronger

[单项选择]All the creatures depend on the sun's rays for the light and warmth which（）us alive.
A. keeps
B. keep
C. kept
D. is keeping

[单项选择]

Sparks created in a lab give off X-rays, scientists announced Monday.
X-rays are a byproduct (副产物) of high-energy electron discharges in the Sun, in exploding stars, and even in lightning. Many scientists did not expect sparks alone to do the trick.
Researchers at Florida Institute of Technology brought their equipment, which had detected X-rays in lightning, into the lab. Half the team expected to see X-rays and the other half did not.
In sparks of 1.5 million to 2 million volts, the researchers indeed recorded X-rays that were remarkably similar to those produced by lightning.
"This amazed us, It opens the door to answering really big questions about lightning by generating it in the lab," said team member Hamid Rassoul. "It also tells us that we have a lot’ to learn about how even small sparks work."
X-rays are a form of electromagnetic radiation, on a spectrum (频谱) that runs from radio waves on the low
A. All the researchers doubt that X-rays can be produced by sparks at first.
B. X-rays produced in lab is just the same with those by lightning.
C. The result of the study is in expectation of every researcher.
D. The researchers detected X-rays in sparks of 1.5 million to 2 million volts.