Based on the information in the passage, what can be inferred about X-ray microscopes in the future
A. They will probably replace electron microscopes altogether.
B. They will eventually he much cheaper to produce than they are now.
C. They will provide information not available from other kinds of microscopes.
D. They will eventually change the illumination range that they now use.
查看答案
What does the passage mainly discuss
A. The detail seen through a microscope.
B. Sources of illumination for microscopes.
C. A new kind of microscope.
D. Outdated microscopic techniques.
铜或镀锌钢等电位联结带的截面不应小于( )。
A. 30mm2
B. 50mm2
C. 80mm2
D. 100mm2
The analogy drawn between the earth and a spaceship is to illustrate the idea of ______ on earth.
A. unlimited resources
B. limited resources
C. recycling
D. regeneration
Which of the following best conveys the' idea that man has been careless and unconcerned in his relationship with nature
A. He has exploited the earth' s resources.
B. He has shown little understanding of nature' s ways.
C. He has abused the earth' s resources.
D. He has not appreciated nature' s beauty and benefits sufficiently.
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