单项选择题

Life on other planets is possible ______.

A．when life-evoking conditions exist
B．only when their conditions match those of the earth
C．when the temperature is neither too hot nor too cold
D．when the atmosphere is not too dry

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热门试题

单项选择题

Life on the planet Jupiter is a possibility which ______.

A．does not exist
B．should not be ruled out
C．excites all scientists
D．has never been explored

单项选择题

When we add qualifications to a condition, we ______.

A．give higher quality to the condition
B．restrict and limit the condition
C．remove all restrictions on the condition
D．enlarge the applicability of the condition