题目

已知直线l的方程为，且直线l与x轴交于点M，圆与x轴交于两点（如图）． （I）过M点的直线交圆于两点，且圆孤恰为圆周的，求直线的方程； （II）求以l为准线，中心在原点，且与圆O恰有两个公共点的椭圆方程； （III）过M点的圆的切线交（II）中的一个椭圆于两点，其中两点在x轴上方，求线段CD的长．When you sit and watch TV hour after hour, do you ever think of what it may be doing on your health?More and more children are becoming overweight and near-sighted   1  they spend too much time in front of the TV. Also, they are growing less and less creative since watching TV. It doesn’t   2  any active thought.Last week, the TV-Turnoff Organization began its ninth TV-Turnoff   3   in the US. The organization encourages people to play games, read books, lie under a tree, talk to family members and friends   4  watching TV.American school children   5  , on average, 1,000 hours a year watching TV-more time than they spend in school. That’s too much, said the doctors   6  organized this year’s TV-Turnoff Week.Doctors say that the   7  children watch television, the more overweight they may become. The fat children eat while they watch the television makes this weight  8  more serious.To keep mentally and physically healthy, children need to take exercise, talk with friend and family, read, and  9  the world around them. Could you go a week without television? It might be    10  for many TV lovers, but why not give it a try?1.A.becauseB.untilC.whetherD.though2.A.findB.needC.loseD.know3.A.DayB.WeekC.MonthD.Year4.A.together withB.because ofC.lots ofD.instead of5.A.costB.spendC.useD.do6.A.whomB.whoseC.whichD.who7.A.laterB.earlierC.longerD.less8.A.problemB.questionC.thingD.lesson9.A.explore(探究)B.inventC.findD.make10.A.easyB.happyC.dangerousD.difficult