as be dangerous between other stop just when something difference
Sharks have been around for a very long time. It means that they have been on earth for thousands of years, and have changed little. A shark is a fish, but it has many ___71___ from a fish. For example, if a shark ___72___ swimming, it will sink（下沉）.
There are ___73___ 200 and 250 kinds of sharks in different size. The largest can be___74___ long as 15 meters. Sharks feed on fish, ___75___ sea animals, or smaller sharks. It is said that one of the most ___76___ sharks is the Great White Shark. They h