单项选择题

Dr. Marcy thinks that life may exist in the 55 Cancri system because ______.

A．he has found the system similar to the solar system
B．he has discovered an Earth-like planet there
C．he has discovered a rocky planet there
D．he has found signs of life in the system

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单项选择题

What can we learn about Dr. Marcy from the passage

A．He is fond of watching Jupiter.
B．He is from a scientist family.
C．He dislikes working with Paul Butler.
D．He is interested in finding life in outer spac

单项选择题

But we stuck with it in the third paragraph means______.

A．they felt discouraged
B．they carried on with it
C．they failed in their attempt
D．they made some progress