A．necessaryB．possibleC．difficultD．good
A. necessary
B. possible
C. difficult
D. good
查看答案
Lake Nyos and Lake Monoun explode B．ecause
A. the gases rise to the top and mix with air.
B. people from the villages turn over the water.
C. scientists have put in a computer system.
D. they have more gases trapped at the bottom than other crater lakes.
A．questionB．exampleC．designD．device
A. question
B. example
C. design
D. device
Power supply systern Was nOt damaged duringthe storm.
A. Right
B. Wrong
C. N0t mentioned
In1996, Arthurc Clarke predicted that
A. biological power sources would be putinto use soon.
B. oil, gas and coal could be repeatedlyused in the future.
C. dependence on non-renewable powersources would be reduced soon.
D. the Chernobyl disaster would happen in two years.
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