What does the "invisible hand"(Paragraph 5) refer to？
A. Supply and demand.
B. Laissez faire.
C. Self-interest.
D. Market mechanism.
A．as a resultB．in the endC．in the wayD．above all things
A. as a result
B. in the end
C. in the way
D. above all things
听力原文：M: I think it's starling to snow:
W: Starting to snow？ The ground's already covered.
What does the woman mean？
A. They're ready for the snow.
B. Once it starts, it'll snow a lot.
C. It bas been snowing for some time.
D. The winter has just begun.
In the passage, the author intends to tell us that
A. those who refuse to be tested for AIDS are justifiable.
B. people should take precautions against AIDS.
C. people should condemn those who are irresponsible.
D. the sick should take the moral responsibility of protecting public health.
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