作业帮36. New studies show that two of Saturns rings ______ longer than the 4.5 billion years since the birth of the Solar System. a. could have lasted b. should have lasted c. would have lasted d. must be lasting 句子什么意思?选哪个?为何?答
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36. New studies show that two of Saturns rings ______ longer than the 4.5 billion years since the birth of the Solar System. a. could have lasted b. should have lasted c. would have lasted d. must be lasting 句子什么意思?选哪个?为何?答
36. New studies show that two of Saturns rings ______ longer than the 4.5 billion years since the birth of the Solar System.
a. could have lasted
b. should have lasted
c. would have lasted
d. must be lasting
句子什么意思?选哪个?为何?
答案选A 为何啊？？？
36. New studies show that two of Saturns rings ______ longer than the 4.5 billion years since the birth of the Solar System. a. could have lasted b. should have lasted c. would have lasted d. must be lasting 句子什么意思?选哪个?为何?答
选C吧
说什么新研究发现土星的光环（?）比太阳系诞生的45亿年还久.
楼下说选should的tx,我觉得should不是推测啊,表示情态什么的.
我晕,我整夜没睡觉搞论文,蒙了头了,是应该选A could,我怎么按成C了汗
could表示一种可能性,.可能比45亿年还要久,只能选could
should是应该,情态上的意味更重,would是过去式的符号,这两个都常用在虚拟语气里,但是这句话不是虚拟语气,是一种推测
B
新研究表明土星环中最外两个环历时比自从45亿年以来太阳系的产生还要久.
since 表明从句用完成时态,排除D
研究表明,也只是推测,should,应该, 所以选 B
could 可能,允许,可以
would will 的过去式