21. What is the main idea of this article?
(A) We should grow crops that won’t need much fresh water.
(B) The lack of fresh water is a problem that keeps getting bigger.
(C) Scientists have invented new ways to save fresh water.
(D) African countries are the hardest hit by shortage of fresh water.

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統計: A(4), B(173), C(24), D(12), E(0) #2030804

詳解 (共 2 筆)

#3495196
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#3801669
Demand for fresh wat...
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