汽车制动时，能做到迅速减速直至停车的能力称为汽车的（）。 A.制动效能 B.制动距离

下列因素中会引起土地价格水平上涨的是( )。

A．政局稳定，资金可以按预期的目标在预期期限内得到回收并取得利润，投资者的投资信心逐步增强

B．政府强化对房地产市场的管理，加强价格管制，实行货币紧缩性政策

C．国家抬高个人所得税起征点

D．投机者哄抬地价，导致土地供不应求，政府因此出台相应管理政策

E．社会秩序良好。环境绿化成效显著，街心公园等公益性项目逐渐增多，人们生活质量逐步提高

阅读理解。

     Today we tell you about some new understanding of why cutting the main branch of a plant

or tree can lead to better development.

     The findings are from researchers on two_continents.Professor Prezemyslaw Prusinkiewicz

of the University of Calgary in Canada led the research with scientists from Britain and Sweden.

Their study appears in the Proceedings of the National Academy of Sciences.

     Researchers have known since the 1930s that the actively growing tip of a plant produces

a hormone(荷尔蒙)called auxin(生长素)．This hormone flows down the main stem.Scientists

say the auxin has an indirect effect on buds(芽)on the side of the stem to prevent branching.

T     hese buds themselves also produce auxin.The research suggests that to grow,they have

to be able to export the hormone into the main stem.But the flow from the stem tip prevents

them from doing this.The researchers wanted to find out how this blocking happens.

     Professor Prusinkiewicz is on leave in Australia,but he sent us an e－mail suggesting a

simple way to understand the process.Think of a major road crowded with traffic.So many

cars are on the main road that the cars on the side roads cannot enter.

     The stem is like the crowded main road.The new research shows that the buds on the

side cannot export their auxin into the main stem because it is too full.But if that main shoot

is pruned(修剪),other buds below it can start exporting.They are no longer prevented from

growing.

     Ottoline Leyser from the University of York says that after a plant is pruned,all the

inhibited(被抑制的)shoot tips compete with each other to grow.In doing this,the branches

influence each other's growth.Nearby shoot tips are more likely to affect each other than those

that are far apart from each other.

     Professor Leyser says the strongest branches grow best,wherever they may be on the

plant.The study found that the main shoot grows the best of all not because of its position at

the top of the plant,but mostly because it got there first.

1．The underlined part "two continents" in Paragraph 2 refers to"__________"．

A．Asia and Africa

B．Africa and Europe

C．North America and Europe

D．Australia and Europe

2．Professor Prusinkiewicz compares the cars on the side roads to __________.

A．plant stems  

B．plant buds

C．the leaves of a plant  

D．the roots of a plant

3．To make the buds on the side of the stem to grow better,the main shoot should __________.

A．be cut off

B．be protected

C．be watered as much as possible

D．be given much auxin

4．According to the passage，which of the following is TRUE?

A．Researchers have recently found out that the growing tip of a plant produces hormones.

B．Auxin has a direct effect on buds to keep branches from growing.

C．Buds on the side of the stem can’t produce hormones.

D．In order to grow，the buds on the side of the stem export the hormones into the main stem.

5．Which of the following may be the best title for this passage?

A．Why shoot tips grow fast?

B．When and how to prune plants?

C．Scientists help cut the mystery behind pruning

D．The great scientist-Prezemyslaw Prusinkiewicz

24．关于中 * * 党、人民政协、和人民代表大会三者的关系，下列说法正确的有

A．人民代表大会在 * * 党和人民政协等国家机构中处于核心地位

B．人民代表大会和人民政协都必须接受中 * * 党的政治领导

C． * * 党和人民政协所作的决定必须得到人民代表大会的认可方可实施

D．人民代表大会同 * * 党、人民政协的关系是领导与被领导、监督与被监督的关系

有关工程价款支付控制的表述，说法错误的是______。

A．按照工程建设质量支付工程价款
B．项目建设初始，应将预付款项拨付施工单位，以保证其顺利进场，项目建设顺利开展
C．工程款项的拨付要与项目建设的计划、预算、程序和进度情况相一致
D．工程价款的支付可采取按月度预拨，在季度或年度验工计价进行结算

接触麻疹疫苗后，机体产生抗体水平最高的时间是接种后（）

A.2周时

B.1个月时

C.6周时

D.2个月时

E.6～8周时