黃金閱讀5.4 第34篇 恐龍的滅絕 - 英檢

想請教各位一個問題Q__Q

倒數第二題 插入句的部份

Paragraph 5 Ir has not been common at Earth’s since the very beginning of
the planet’s history. Because it usually exists in a metallic state, it was
preferentially incorporated in Earth’s core as the planet cooled and
consolidated. lr is found in high concentrations in some meteorites, in which
the solar system’s original chemical composition is preserved. Even today,
microscopic meteorites continually bombard Earth, falling on both land and
sea. By measuring how many of these meteorites fall to Earth over a given
period of time, scientists can estimate how long it might have taken to
deposit the observed amount of lr in the boundary clay. ■These calculations
suggest that a period of about one million years would have been required. ■
However, other reliable evidence suggests that the deposition of the boundary
clay could not have taken one million years. ■So the unusually high
concentration of lr seems to require a special explanation. ■


13. Look at the four squares [■] that indicate where the following sentence
could be added to the passage.

Consequently, the idea that the lr in the boundary clay came from microscopic
meteorites cannot be accepted.

Where would the sentence best fit?


答案是1可是我選3
為什麼是在1呢?
不是到了第2個空格都講完了 才解釋了不合理的地方?
中文如下

(空格一)這種計算表明形成這種沉積可能需要一百萬年。
(空格二)然而其他可靠的證據則表明沉積這層粘土
可能不需要一百萬年。
(空格三)所以這種不正常的銥的富集可能需要一種特殊的解釋。(空格四)





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