three__________(序数词)

you，let，help，me

____________________________

()“CanIhelpyou?”“I'dlike______bagsofrice.”

“Earlytobed，earlytorise”makesamanhealthy,wealthyandwise.It'sgoodforthebody.Thisisanoldsaying.Haveyouheardofitbefore?Itmeansthatwemustgotobedearlyatnight，andgetupearlyinthemorning.Thenweshallbehealthy.Weshallalsoberichandclever.Thatistrue.Thebodymusthaveenoughsleeptobehealthy.Childrenofyoungageshouldhaveenoughsleep，ortheycan'tdotheirworkverywell.Theywillnotbewiseandtheymaynotbecome。wealthy!.Thebodyalsoneedsexercise:walking,running,jumping,swimming,playinggamesandallother。exercise.Exercisekeepsthebodystrong.Exercisealsohelpsthebloodtomovearoundinsidethe.body.Thisisveryimportant.Ourbloodtakesfoodtoallpartsofourbody.Theheadalsoneeds.blood.Exercisehelpsustothinkbetter.

根据短文内容，回答问题.

1.Whatdoes“earlytobed.earlytorise”mean?

2.Whatmustthebodyhavetobehealthy?

3.WhatwillhappentoChildrenofyoungagewhodon'thaveenoughsleep?

4.Whatkeepsthebodystrong?

5.Whattakesfoodtoallpartsofourbody?

如图是为了检验某种防护罩承受冲击能力的实验装置，M是半径为R=l.0m、固定在竖直平面内的l/2光滑圆弧轨道，轨道上端切线水平.N为待检验的防护罩部分曲面，该曲面在竖直面内的截面是半径的1/4圆弧，、圆弧下端切线水平且圆心恰好位于M轨轨道的上端点，M的下端相切处置放水平向左的弹簧枪，弹簧枪可发射速度不同的、质量均为m=0.1kg的小钢珠。设某次发射的钢珠沿轨道恰好能经过M的上端点，水一飞出后落到N上的P点处取g=lOm/s2，求：

(1)发射该钢珠前，弹簧的弹性势能Ep;

(2)钢珠落到圆弧上点P时速度的大小Vp；