问题描述:
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???
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???
问题解答:
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