Create ten questions about sharks

(1) How many species of sharks are there?
(2) What do sharks eat?
(3) How long is an average shark's lifespan?
(4) Can sharks hear?
(5) Do sharks sleep?
(6) How fast do they swim?
(7) Do they have good eyesight?
(8) Do they lay eggs or give birth?
(9) How do they detect prey?
(10) Are all sharks dangerous to human?
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some extra ones:
- Should we protect sharks?
- How many people are attacked by sharks on average per year?
- How do sharks attack people?
- How can you tell whether it is a male of a female shark?
- Are sharks warm-blooded or cold-blooded?

http://en.wikipedia.org/wiki/Shark
The above link can help you get more than 100 sentences about sharks.
good luck o ...

2007-03-17 14:54:19 補充：
ex : "Sharks are fish with a full cartilaginous skeleton and a streamlined body. They respire with the use of five to seven gill slits. "