Sharks have been on earth for 1 of years．There are between 200 and 250 kinds of sharks．They come in different 2 ．The largest can be as long as 15 metres．It eats plants from the sea, but many sharks feed 3 fish, other sea animals, smaller sharks and 4 they eat people．It is said that one of the most 5 sharks in the great White Shark．They have attacked(袭击)a number of people off the 6 of America．Australia, New Zealand and South Africa also have shark attacks．In some places there are watchtowers on the beaches to warn people about sharks in the water．When a shark 7 , a bell rings to 8 the people to get out of the water．Sharks 9 about 100 people a year in the world．Perhaps the shark just thinks that the person is a kind of 10 animal, or something good to eat．