设那么f(n+1)-f(n)等于（） A.A B.B C.C D.D

根据文章内容，判断正（T）、误（F）。

     Are you an impolite student? I hope your answer is "no"! What can you do to be a polite student? Have

you ever had these impolite behaviors?

     a. Do you usually play loud music in the evening?

     b. When you see the food you like, but there're many people waiting in line to buy it, will you cut in line?

     c. When you are eating food On the street, will you throw it on the ground?

     d. If you order a pizza half an hour ago, but it hasn't arrived yet, will you get annoyed?

     Manners are taught as soon as children can understand what parents are talking about. Maybe your father

and mother have told you thousands of times about what you should do and what you should not do. For

example, your parents told you that you shouldn't interrupt (打断) when your parents are talking.

     In some western countries, the first manner the children should learn is to make themselves clean. Parents

believe that keeping children clean is really important. Whether the children are at home or school, parents will

always tell them not to throw things at will (随意地).

( )1. It is OK to play loud music in the evening.

( )2. Manners are about what you should do and what you should not do.

( )3. It's impolite to cut in line when there are many people waiting in line to buy some food.

( )4. In Western countries, you can throw things at will when you are at home.

( )5. In the writer's opinion, if you want to be a polite student, you shouldn't have the four impolite behaviors.

在C、H、O、S、Na五种元素中，选择适当元素，组成符合下列要求的物质，请将其化学式填入空格中。

（1）天然气的主要成分__________；

（2）具有刺激性气味的一种空气污染气体________；

（3）最理想的可作高能燃料的单质_______；

（4）易与血红蛋白结合使人中毒的氧化物_______；

（5）实验室常用的酸____________。

以下说法正确的是________。

A．现在手持设备还都不能上网

B．现在家用计算机和多媒体计算机完全不一样

C．现在笔记本电脑与台式机性能相差不多

D．现在高档微机与工作站区别很大

     Every culture has a recognized point when a child becomes an adult, when rules must be followed

and tests passed.

     In China, although teenagers can get their ID cards at 16, many only see themselves as an adult

when they are 18. In the US, where everyone drives, the main step to the freedom of adult life is

learning to drive. At 16, American teens take their driving test. When they have their license, they drive

into the grownup world. 

     "Nobody wants to ride the cheese bus to school," said Eleanor Fulham, 17. She brought the

pressure back to memory, especially for kids from wealthier families. "It's like you're not cool if you

don't have a car," she said.

     According to recent research, 41% of 16 to 19yearolds in the US own cars, up from 23% in 1985.  

Although, most of these cars are bought by parents, some teens get parttime jobs to help pay.

     Not all families can afford cars for their children. In cities with subways and limited parking, some

teenagers don't want them. But in rich suburban areas without subways, and where bicycles are more

for fun than transportation, it is strange for a teenager not to have a car.

     But police say 16yearolds have almost three times more accidents than 18 to 19yearolds. This has

made many parents pause before letting their kids drive.

     Julie Sussman, of Virginia, decided that her son Chad, 15, will wait until he is 17 to apply for his

learner's permit.

     Chad said he has accepted his parents' decision, although it has caused some teasing from his

friends. "They say that I am unlucky," he said, "But I'd rather be alive than driving, and I don't really

trust my friends on the road, either."

     In China as more families get cars, more 18yearolds learn to drive. Will this become a big step to

becoming an adult?

1. Which may serve as the best title of the article?

A. Cars Helping You to GrowUp

B. Driving into the GrownUp World

C. Teenagers' Driving in America

D. Recognized Point of Becoming an Adult

2. 16yearold drivers have more accidents possibly because________.

A. they want to show themselves off

B. they are never experienced drivers

C. older people always drive better

D. they never drive carefully on the road

3. Which may NOT be taken into consideration when deciding whether to buy a car?

A. How well off the family is.

B. Whether the kid is old enough.

C. What traffic condition there is around.

D. Whether it's practically needed.

团队领导方式没有好坏之分，关键是（）。

A.看它是否代表领导层的意思

B.看它是否代表团队成员的利益

C.看它是否适合团队当前的情况和发展

D.看它是否适应其他团队的发展