Question

　　Coral reefs are formed by millions of tiny animals called corals． Corals secrete limestone, which hardens into cup-like shapes that stick together． As the animals die, younger corals attach themselves to the old cups． In this way the reef is built up．

　　Sometimes corals form odd shapes． Organ-pipe coral looks like the pipes of an organ． Staghorn coral looks like antlers． And brain coral looks like the human brain．

　　Precious corals are found in parts of the Mediterranean Sea and in the Sea of Japan． They are valuable as well as beautiful, and their bright red cores are used for jewelry．

　　The most famous coral reef in the world is Australia's Great Barrier Reef． It is about twenty to thirty miles from shore and more than twelve hundred miles long．

1．Coral reefs are formed by________．

A．small animals B． large insects C． deer's antlers　　D． organ pipes

2． The limestone______．

A．takes a cup-like shape B． hardens C． sticks together D． All of the above

3．Which happens first?

A．The corals die．　　 B．The corals secrete limestone．

C．The reef builds up． D．Younger corals attach themselves．

4．Fan coral probably________．

A．waves in the water B． is used to make fans

C． looks like a fan　　D． All of the above

5．Precious corals are valuable probably because they________．

A．have bright red cores　　 B． are found in the Mediterranean

C．have unusual shapes　　 D．look like the human brain

6．The most famous coral reef is near__________．

A． China B． Japan C． Australia D． Hawaii

7．The reef is probably famous because of its________．

A． distance from shore B． length C． location D． shape

Answer 1

答案：A;D;B;C;A;C;B
解析：

提示：