解析:那个流浪汉把他所有的物品都放在背包里。A 卡车司机 B流浪汉 C凶手 D老人

Is the Sea Getting Saltier?

Have you ever noticed that, in the summer, when your sweat dries it will leave marks on your

T-shirt? The marks are tiny bits of salt. If you go to the seaside, you will know that seawater does the same to your clothes, because it also has a lot of salt in it.

Water evaporates from the surface of the sea but the salt remains. Have you ever thought

about whether the seas will keep getting saltier? The answer is no. The oceans have stayed at about 3.5 per cent salt content for hundreds of millions of years. It maintains a constant level of salt in different ways.

Pick up a clamshell and weigh it in your hand. It is heavy. All creatures need sodium to live

and most need calcium to build bones and shells. The clam, like all sea creatures, gets its sodium and calcium from seawater. When creatures die, their salt is locked up in bones and shells, which drop to the bottom of the sea.

Reactions between seawater and rocks are not just one way. Sea salt not only dissolves from

rocks, it also reacts with the rocks of the ocean crust, and volcanic lava. The reactions take some of the salts in seawater away from the sea.

The outer hard crust of Earth is made up of a dozen hard plates that drift on extremely hot,

soft rock, like floating islands on a sea. The heat within Earth is not the same everywhere and the plates move due to the heat. When an ocean plate bumps（碰击） into a land plate, the less dense land plate floats over the ocean one. The ocean floor gets pushed under, and its salty rocks, along with shells and bones, are lost deep within Earth.

So, that's why the seas are salty but don't get any saltier.

1.When the sweat on your T-shirt dries, it will leave some marks of salt

A.Right B.Wrong C.Not mentioned 正确答案:A

解析:该题说的是：当体恤衫上的汗干了之后，会留下一些盐渍。文章的第一段第二句就表明在体恤衫上留下的印记是少量的盐渍

2.The water in the sea will get saltier and saltier because water evaporates and the salt remains

A.Right B.Wrong C.Not mentioned 正确答案:B

解析:该题说的是：水分蒸发.盐分滞留导致海水变得越来越咸。第二段的第三句说答案是否定的，因此这句话的表述是错误的

3.All creatures must depend on sodium and build bones and shells