帮忙作一篇高中语法填空

帮忙作一篇高中语法填空
The sea has always interested man.From it he can get food,minerals,and treasure.For thousands of years,he could sail on it._____(1)he could not go far beneath its surface.
Man wants to explore deep into the sea.However,he must breathe air,he cannot stay under the water's surface for any ______(long)(2)of time.To explore the deep water,man faces even more dangers and problems.
A diver _____(3)wants to stay under water for more than a few minutes must breathe air _____(4)a special mixture of gases.He can wear a diving suit and have air _____(pump)(5)to him from above.Or he can carry a tank of air on his back and breathe through a hose and a mouthpiece.
Water weighs 800 times as much as air.____(push)(6)by tons of water,diver's bodies are under great pressure.
When a driver is under great pressure,his blood takes ____(7)some of the gases he breathes.As he rises to the surface ,the water pressure becomes _____(8),if the driver rises too quickly,the gases in his blood from bubbles.The diver is then suffering _____(9)the bends(潜水员病）.The bendscan cause a diver to double up in pain.They can____(10)kill him.
尤其是第2,5,7,9题最好解释一下为什么