TPO 8 reading RUNNING WATER ON MARS - 英檢

想請問TPO 8的閱讀RUNNING WATER ON MARS第二題


Paragraph 1 Photographic evidence suggests that liquid water once existed in
great quantity on the surface of Mars. Two types of flow features are seen:
runoff channels and outflow channels. Runoff channels are found in the southern
highlands. These flow features are extensive systems─sometimes hundreds of
kilometers in total length─of interconnecting, twisting channels that seem to
merge into larger, wider channels. They bear a strong resemblance to river
systems on Earth, and geologists think that they are dried-up beds of long-gone
rivers that once carried rainfall on Mars from the mountains down into the
valleys. Runoff channels on Mars speak of a time 4 billion years ago (the age
of the Martian highlands), when the atmosphere was thicker, the surface warmer,
and liquid water widespread.


2. What does the discussion in paragraph 1 of runoff channels in the southern highlands suggest about Mars?
○The atmosphere of Mars was once thinner than it is today.
○Large amounts of rain once fell on parts of Mars.
○The river systems of Mars were once more extensive than Earth’s.
○The rivers of Mars began to dry up about 4 billion years ago.

想問位什麼答案是2不是1呢???
最後一句話的意思不是可以對照答案1嗎???

謝謝指教!!


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