[阅读选择]In the next stage， from three to five years old， curiosity knows no bounds. Every type of suitable toy should be made available to the child， for trying out， experimenting and learning， for discovering his own particular ability. Bricks and jigsaws(七巧板) and construction toys; painting， scribbling(涂鸦) and making things; Sand and water play; toys for imaginative and pretending play; the first social games for learning to play and get on with others.
We learn from the passage that a child has boundless curiosity______.
A.when he is two.
B.when he is around four.
C.when he is six.
D.when he is eight.
答案解析：根据In the next stage, from three to five years old, curiosity knows no bounds可以得出答案是B。
[阅读选择]But even if every large city purified and reused its water， we still would not have enough. Where could we turn next? To the oceans! All we‘d have to do to make use of the vast amount of sea-water is —— remove the salt. This salt-removing process is already in use in many parts of the world.
According to the passage， sea-water can be turned into fresh water by_____
A.heating it up.
B.treating it with chemicals.
C.taking salt out of it.
D.drying it up.
答案解析：海水之所以不能饮用就是因为它是咸的。答题依据是本段的remove the salt即take salt out。