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美国科学家在一海底河床发现了一些古生物的足迹化石,经考证,留下这些足迹的生物距今5.7亿年,这把世界上最早的有腿生物生活的年代向前推进了3000万年。科学家们曾经以为,在寒武纪之前地球上主要存在的可能仅仅是一些生物以及一些简单的单细胞动物。地球科学教授Loren Babock表示:“一直都在研究在埃迪卡拉纪时期出现复杂生物如软珊瑚、节枝动物以及扁虫的可腿走路的动物化石足迹后,该项推的可能性就大大被提高了。”根据这段文字,下列推断正确的一项是:
A.科学家们认为,在寒武纪之前地球上不可能存在生物
B.可以肯定,5.7亿年前的有腿生物生活在海底水世界
C.埃迪卡拉纪时期比寒武纪时期距离今天的时间更久远
D.在此之前,对有腿生物的研究仅限与微生物及单细胞动物

A.7亿年,这把世界上最早的有腿生物生活的年代向前推进了3000万年。科学家们曾经以为,在寒武纪之前地球上主要存在的可能仅仅是一些生物以及一些简单的单细胞动物。地球科学教授Loren
B.科学家们认为,在寒武纪之前地球上不可能存在生物
B.可以肯定,5.7亿年前的有腿生物生活在海底水世界
C.埃迪卡拉纪时期比寒武纪时期距离今天的时间更久远

【参考答案】

B
解析:“科学家们曾经以为,在寒武纪之前地球上主要存在的可能仅仅是一些微生物以及一些简单的单细胞动物”,所以A不对。题干只说科学家在一海底河床表面发现了一些古生物的足迹化石,并没有说这些古生物本来就是生活在海底的,沧海桑田,今天的海底也许是曾经的高山,所以C不对。题干中说这些古生物足迹化石...

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A.B.
C.
D.
Notes:
crop
E.支持
benevolent
F.(他似乎要开始了)
swirls
G.emphasis
H.
B.degree
I.
C.way
J.
D.extent