题目内容：

Help Hermit Crabs

Hermit crabs are nature's recyclers. They eat waste and help keep oceans and shores clean. Unlike other crabs，the hermit crab has a thin outer shell over its soft tail. This makes the hermit crab easy prey for hungry predators(天敌).Hermit crabs stay safe by living in old seashells. A hermit crab is picky(狡猾);it tries on many shells until it finds one that fits just right. In recent years，however，many hermit crabs have had trouble finding their perfect homes. What is the problems There are not enough shells to go around!

One reason for the seashell shortage is that ocean water is not as clean as it once was.This has caused chemical changes to sea water.Some sea animals，like snails，are affected by these changes.  Now there are fewer snails making shells. People visiting the beach often take shells home as souvenirs(纪念品).This is another problem.Other people even take shells for their own pet hermit crabs!They do not realize that hermit crabs in the wild need those shells too.

Now people are working to solve this hermit crab housing shortage. They are teaching beach-Boers to leave seashells where they belong--at the seashore!Some people even make fake seashells that they hope the hermit crabs will like.For example，a group called Project Shelter invited people who visited their website to create different designs for hermit crab shells.

These designers had a lot to consider. What kind of material should be used to build a seashells.The material must be light enough for the hermit crab to carry，but strong enough to protect the crab from predators. The man-made shells could not contain glue or any other substance(物质)that might harm a hermit crab. Another challenge with building a hermit crab home was the opening to the shell. Too big would mean the crab would not feel safe.Too small would be uncomfortable，and the crab would not want to move in.

The Project Shelter shells are placed in the wild for hermit crabs to find.Lucky hermit crabs can move into these new dream homes.

1.Where can hermit crabs stay safe?

A. In different old seashells.    B. Behind the waste they'll eat.

C. In their own thin outer shells.    D. Under the stones at the seashore.

2.According to the passage，what should be put in the webs?

A. The methods to recycle the wastes.    B. The ways to help the hermit crabs.

C. The materials of seashells.    D. The designs of websites.

3.What does the underlined word“fake" in Para. 3 mean?

A. man-made    B. perfect

C. hard    D. comfortable

4.What is the passage mainly about?

A. The Project Shelter Group.    B. The shortage of the seashell.

C. New homes for hermit crabs.    D. The recyclers of the nature.