Kelly Christopher, a student at Lutheran High School in California, US, loves oranges. One day last week, she used a pole(竿子) to pick oranges off trees and collect them in baskets. It’s the first time in her 15 years she’s picked fruit from trees.

"This is quite different from buying oranges in the supermarket," said Christopher. "Every time I eat an orange, I’ll remember this experience."  

Christopher was one of the 30 student volunteers at Soil Born Farms. She volunteered as part of a project which was set up in 2009 to help homeowners in South Land Park pick oranges and other fruits out of their backyards. Before, the fruit would rot on the ground or get eaten by animals. Now the fruit is donated to those who need it.

"It is good for many people", said Randy Stannard, who works for the project. "The homeowner gets fruit picked and more people can have healthy food."

"Two harvests (收成 ) were organized in 2009 and volunteers picked 3,000 pounds (1,360kg) of fruit", Stannard said. In 2010, the number was 20,000. This year, Soil Born Farms hopes to get 40,000 pounds. They will harvest every weekend from January to April.

Shannon Galloway, Christopher’s science teacher, brought her students into the project this year.

"You’re making use of a resource that might be wasted," she said. "I think it’s meaningful to everyone."

Donato Frazier, 15, always climbs up a ladder(梯子) and gets on the top of the tree.

"Standing on the treetop is pretty cool," Frazier said. "I can see clearly that many baskets are filled up, and even see that many people are eating healthy fruit because of our volunteer work."                                          

71. Christopher and other students went to pick fruits from real trees because they wanted to _____.

A. have some fresh fruit for themselves    B. make some money by selling fruit

C. provide people with more healthy fruit   D. buy some cheap fruit from their neighbors

小题1: When was the project set up?

A．In 2008.

B．In 2009.

C．In 2010.

D．In 2011.小题2:What will happen to the fruit if they don’t help the homeowners pick it?

A．The fruit will rot or be eaten by small animals.

B．People who need the fruit will come to pick it.

C．The fruit will be used as a resource for research.

D．Homeowners will pick the fruit and sell it.小题3: What does the underlined word “mean?

A．资源

B．调查

C．对策

D．娱乐小题4:How do the students feel about their work?

A．It’s interesting and easy.

B．It’s meaningless and hard.

C．It’s meaningful and exciting.

D．It’s tiring and boring.

研究氮及其化合物的性质在人类进步过程中具有极为重要的意义。

(1)自然界中存在着各种固氮反应，写出大气中雷电作用时的固氮反应的化学方程式：__________________

(2)已知反应：

①2H₂(g)+O₂(g)2H₂O(g) △H=-483.6kj/mol

②N₂(g)+3H₂(g)2NH₃(g) △H=-92.4kJ/mol

③4NH₃(g)+5O₂(g)4NO(g)+6H₂O(g) △H=-905kJ/mol

则反应④4NH₃(g)+3O₂(g)2N₂(g)+6H₂O(g)的△H=___________。如图是在一个密闭容器内，在催化剂作用下，一定量的氨气与氧气的混合气体在不同温度时的生成物及生成物含量与温度的关系图：温度较低时以反应_______（选填上述已知反应序号“①、②、③或④”）为主，当温度高于900℃时，NO产率下降的原因____。

(3)在实验室中，某同学利用下列试剂及器材完成的实验能够证明NH₃·H₂O是弱电解质的是_________（选填字母代号）。

a．用氨水做导电性实验，灯泡昏暗

b．将氨水滴入AlCl₃溶液中，产生白色沉淀

c．常温下，用pH试纸测得0.1mol/L氨水的pH<13

d．用湿润的篮色石蕊试纸测得NH₄Cl溶液为红色

(4)在一定温度下，在一容积为2L的密闭容器中，通入一定量NO₂和N₂O₄的混合气体，测得这两种物质的浓度随时间的变化关系如图所示。0～10min内N₂O₄的化学反应速率v(N₂O₄)=_______，在第25min时，容器内两种物质的浓度突然发生变化，出现这种现象的原因是_________，35min时， 反应N₂O₄2NO₂的化学平衡常数K=________。