In Australia there is a famous island called Fraser Island．A great many visitors come here for holidays every year．Why？The reason is that it is special．（56）　　．In fact，it is the largest sand island in the world．It's about 200 kilometers long and 240 kilometers wide．

   Though the island is a popular place of interest，there is no airport on the island．The long beach along the east coast works as the airport．（57）　　．

   On the island there are sand hills without any plants，but there are forests with old trees，beautiful flowers and over a hundred lakes，too．（58）　　．

   Every year，visitors come to enjoy the island's natural beauty．People like camping and hiking there．（59）　　．Animals were killed for food and this made them in danger of extinction （灭绝）．They threw rubbish everywhere，and the lakes were seriously polluted．

（60）　　．Rules have been set up．For example，visitors are not allowed to use motorboats （摩托艇） or go fishing in the lakes，and they mustn't leave any rubbish．

A．Planes arrive and leave from here

B．Anyone who breaks the rules w il be pun i shed

C．The island is completely made of sand

D．Unluckily，visitors have caused many problems

E．Many kinds of birds and animals live in the forest

F．So it is time to protect the environment of the island．