9. It is reported that New Culture Square ________ in our city next year.
A. will be built B. were built C. have built D. will build
8. Each time tourists travel to Beijing, they _________ the Forbidden City.
A. will be shown up B. will be shown around C. will show around D. will show to
7. Not only Jim but also his parents _________ a few interesting places since they came to China.
A. will visit B. has visited C. have visited D. visited
6. Please __________ the water when you brush your teeth.
A. take down B. turn up C. take away D. turn off
5. Some people waste too much water. They don’t believe that it can _________ some day.
A. keep out B. run out C. be run out D. run out of
4. I think we must give up using plastic bags to ___________ our earth.
A. produce B. protect C. provide D. pollute
3. Driving after drinking wine ________ in China.
A. allows B. doesn’t allow C. is allowed D. isn’t allowed
2. The government should stop them from _______ trees in the forest.
A. cutting down B. putting down C. taking down D. letting down
一、单项选择
1. —What should I do to live _____ green life?—I think you go by _____ bike instead of driving your car.
A. a; a B. the; / C. a; / D. /; /
24.(本小题14分)
解:(1)将x=0代入y=(x-2)2+1,得y=5.
则抛物线y=(x-2)2+1与y轴的交点A的坐标为(0,5). ………………1分
抛物线y=(x-2)2+1的顶点B的坐标为(2,1). ………………2分
设抛物线y=(x-2)2+1的友好直线AB的表达式为y=kx+b,
则
解,得
…………………………4分
∴抛物线y=(x-2)2+1的友好直线AB的表达式为y=-2x+5. ………5分
抛物线y=(x-2)2+1的友好四边形的面积为20. ……………………6分
(2)如图,抛物线
的顶点为B(h,k),
作BE⊥AC于点E,
由题意得四边形ABCD是平行四边形,
直线y=x-3与y轴的交点A的坐标为(0,-3),
所以,点C的坐标为(0,3),可得:AC=6. …………8分
∵平行四边形ABCD的面积为12,
∴S△ABC=6即S△ABC=
AC•BE=6,
∴BE=2, …………………………9分
∵h>0,即顶点B在y轴的右侧,∴h=2.
∵点b在直线y=x-3上,
∴顶点B的坐标为(2,-1), ………………………………10分
又抛物线经过点A(0,-3),
∴a=-
,∴抛物线表达式为y=
. …………………………11分
(3)①当抛物线
的友好四边形ABCD是菱形时,如图.
AC⊥BD,OA=OC,OB=OD,
∵AC在y轴上,AC⊥BD,
∴此时BD在x轴上,∴点B的坐标为(h,0). …………12分
∵点B在直线y=-2x+m上,
∴把y=0代入y=-2x+m,得x=
.
∴抛物线顶点B的坐标为(
,0). ………………………13分
②当抛物线
的友好四边形ABCD是矩形时,
∴抛物线顶点B的坐标为B(
,
).……………14分
说明:以上各题的其他解法请参照此标准评分.
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