单项选择题

The new idea the passage presents us is about ___________.

A．designing a new type of heat exchanger
B．storing winter cold for use in summer
C．establishing an underground air-conditional system
D．creating an efficient and economical air-conditioning system
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单项选择题
It can be inferred from the passage that on other planets
A．there is no oxygen for creating life
B．there is no suitable temperature for creating life
C．living things of different kinds may exist
D．living things similar to that on earth may exist
单项选择题
Scientists cannot create actual life in laboratory because ___________.
A．they can't complete endless biochemical reactions
B．they can't have the same conditions that nature has
C．they lack of millions and millions years of time
D．they lack of enough nucleic acid molecules
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