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.
詳解 (共 2 筆)
未解鎖
水是我們最重要的自然資源。然而,儘管它覆...
未解鎖
Demand for fresh wat...