热点试题

[ 数学 ] 已知:关于x的二次函数(a>0),点A(n,y1)、B(n+1,y2)、C(n+2,y3)

已知:关于x的二次函数(a>0),点A(n,y1)、B(n+1,y2)、C(n+2,y3)都在这个二次函数的图象上,其中n为正整数.
(1)y1=y2,请说明a必为奇数;
(2)设a=11,求使y1≤y2≤y3成立的所有n的值;
(3)对于给定的正实数a,是否存在n,使△ABC是以AC为底边的等腰三角形?如果存在,求n的值(用含a的代数式表示);如果不存在,请说明理由.

2016-05-18 | 0

[ 数学 ] 下图中,最大平行四边形的面积是36平方厘米,阴影部分的面积是 [     ] A.9平方厘

下图中,最大平行四边形的面积是36平方厘米,阴影部分的面积是
[    ]
A.9平方厘米
B.18平方厘米
C.36平方厘米

2016-05-21 | 0

[ 数学 ] 计算下面各题(1)34+27(2)23-49+518(3)310-(56-45)(4)1-

计算下面各题
(1)
3
4
+
2
7

(2)
2
3
-
4
9
+
5
18

(3)
3
10
-(
5
6
-
4
5

(4)1-
2
9
-
5
12

2016-05-21 | 0

[ 数学 ] (1)解方程lg(3-x)-lg(3+x)=lg(1-x)-lg(2x+1);(2)解不等

(1)解方程lg(3-x)-lg(3+x)=lg(1-x)-lg(2x+1);
(2)解不等式
2x+5
>x+1.

2016-05-22 | 0

[ 数学 ] n是正数,园x2+y2-(4n+2)x-2ny+4n2+4n+1=0,当n变化时得到不同的

n是正数,园x2+y2-(4n+2)x-2ny+4n2+4n+1=0,当n变化时得到不同的圆,这些圆的公切线是(  )
A.y=0 B.4x-3y-4=0
C.都不是 D.y=0和4x-3y-4=0

2016-05-25 | 0

[ 英语 ] —Do you like weekends   —             . [    

—Do you like weekends?   —             .[    ]
A. Yes, I do      
B. No, I do      
C. Yes, I like

2016-05-28 | 0

[ 英语 ] 将下列单词组成正确句子。 1.  red   white   and   blue   i

将下列单词组成正确句子。
1.  red   white   and   blue   is   it
                                                            
2.  is   here   the   a   map   of   U. S.
                                                           
3.  speak   English   they
                                                           

2016-05-28 | 0

[ 英语 ] Sit _____ you like.A.whereB.at the placeC.as

Sit _____ you like.
A.whereB.at the placeC.as D.wherever

2016-05-29 | 0

[ 英语 ] What’s the greenest place in America If you a

What’s the greenest place in America? If you answered something like the warm sunlight of Santa Barbara, you’d be wrong. The greenest place in America has almost no sign of nature— the buildings outnumber the trees— and the air isn’t all that great. What it has is density(密度)and efficiency— the twin qualities that finally define green in the global warming time. Applying those standards,the greenest place in America is New York City— particularly,the overcrowded,overpriced island of Manhattan, which produces 30% less per-capita(人均)greenhouse gas than that of the nation.
It’s that density that makes Manhattan so green. Manhattan’s population density is 800 times the national average. Density comes with negatives,certainly— small living spaces,air pollution— but it also enables amazing efficiencies.Over 80% of Manhattanites travel to work by public transport, by bike or on foot— compared to an average of about 8% everywhere else in the country. Manhattan’s apartment buildings are far more energy-efficient than the houses in the suburbs.
What’s true of New York City is more or less true of other American urban areas, which explains why a growing part of the environmental movement now focuses on greening cities, hoping to attract more Americans back downtown. There’s an effort to make cities more sustainable(可持续的),by improving public transport,reducing air pollution and upgrading energy efficiency. But even more important, it is quite urgent to change decades of government policies that have been in favor of the suburbs,with disastrous consequences for energy,the environment and the climate.
That’s exactly the difficult point. For all the high efficiency and convenience and richness of living in a city,there are disadvantages too.New York,for example,has some of the highest childhood asthma(哮喘)rates in the U.S.
So it’s welcome news that New York has continued to push its P1aNYC scheme, a long-term program to make the city greener and more sustainable over the next decades. Recently it announced an update to the plan that includes phasing out heavy heating oils in New York City apartment buildings by 2030,to be replaced with cleaner natural gas.
小题1:Manhattan is considered as the greenest place in America because of its__________
A.buildings and treesB.density and efficiency
C.sunlight and natureD.transport and population
小题2:We can infer from the passage that___________.
A.New Yorkers have urged the city government to carry out green policies
B.the public transport and living space are quite satisfactory in New York
C.life in the countryside is more comfortable and energy efficient than that in cities
D.the significance of making cities greener is gained in promoting energy efficiency
小题3:The underlined word “it” in the last paragraph refers to___________.
A.New York cityB.PlaNYC scheme
C.ManhattanD.Santa Barbara
小题4:The underlined part “phasing out” in the last paragraph probably means___________.
A.rapidly promoting dealing with
B.widely suggesting researching on
C.gradually stopping using
D.immediately forbidding producing
小题5:What would be the best title for the passage?
A.Manhattan the Greenest Place in America?
B.The Higher Density,the Greener City?
C.PlaNYC Scheme:New York City’s Future
D.Living in Cities Does Good to the Environment

2016-05-29 | 0

[ 物理 ] 在研究下述运动时,能把物体看做质点的是A.研究跳水运动员在空中的跳水动作时B.研究飞往火星

在研究下述运动时,能把物体看做质点的是
A.研究跳水运动员在空中的跳水动作时
B.研究飞往火星的火星探测器最佳运行轨道时
C.研究太阳发生日食现象时
D.研究天宫一号和神舟八号实现交会对接时

2016-05-31 | 0