帮忙作一篇高中语法填空

Theseahasalwaysinterestedman.Fromithecangetfood,minerals,andtreasure.Forthousandsofyears,hecouldsailonit._____(1)hecouldnotgofarbeneathitssurface.

Manwantstoexploredeepintothesea.However,hemustbreatheair,hecannotstayunderthewater'ssurfaceforany______(long)(2)oftime.Toexplorethedeepwater,manfacesevenmoredangersandproblems.

Adiver_____(3)wantstostayunderwaterformorethanafewminutesmustbreatheair_____(4)aspecialmixtureofgases.Hecanwearadivingsuitandhaveair_____(pump)(5)tohimfromabove.Orhecancarryatankofaironhisbackandbreathethroughahoseandamouthpiece.

Waterweighs800timesasmuchasair.____(push)(6)bytonsofwater,diver'sbodiesareundergreatpressure.

Whenadriverisundergreatpressure,hisbloodtakes____(7)someofthegaseshebreathes.Asherisestothesurface,thewaterpressurebecomes_____(8),ifthedriverrisestooquickly,thegasesinhisbloodfrombubbles.Thediveristhensuffering_____(9)thebends(潜水员病）.Thebendscancauseadivertodoubleupinpain.Theycan____(10)killhim.

尤其是第2,5,7,9题最好解释一下为什么