3.若函数f(x)对定义域内的任意x满足：f(x+a)=f(x－a),则2a为函数f(x)的周期。

(若f(x)满足f(a+x)=f(a－x)则f(x)的图象以x=a为图象的对称轴，应注意二者的区别)

2.若T是周期，则k·T(k≠0,k∈Z)也是周期，所有周期中最小的正数叫最小正周期。一般所说的周期是指函数的最小正周期。

周期函数并非所都有最小正周期。如常函数f(x)=C；

1.函数的周期性定义：

若T为非零常数，对于定义域内的任一x，使恒成立，则f(x)叫做周期函数，T叫做这个函数的一个周期。

周期函数定义域必是无界的

2.理解函数的周期性与图象的对称性之间的关系，会运用函数的周期性处理一些简单问题。

1.理解函数周期性的概念，会用定义判定函数的周期；

5. What is the best title for the passage?

　 A. How to Package a Product　 B. How to Make an Advertisement

　 C. How to Sell Product　 D. How to Attract More Buyers

议论文：1猜测词义 2推断题 3推断题 4细节题 5主旨题　　　 (CCBAD)

C

Exercise is one of the few factors with a positive role in long-term maintenance of body weight. Unfortunately, that message has not gotten through to the average American, who would rather try switching to "light" beer and low-calorie bread than increase physical exertion(用力). The Centers for Disease Control, for example, found that fewer than one-fourth of overweight adults who were trying to shed pounds said they were combining exercise with their diet. 　 In rejecting exercise, some people may be discouraged too much by caloric-expenditure (热量消耗)charts; for example, one would have to briskly walk three miles just to work off the 275 calories in one delicious Danish pastry (小甜饼). Even exercise professionals concede half a point here. "Exercise by itself is a very tough way to lose weight," says York Onnen, program director of the President's Council on Physical Fitness and Sports. 　 Still, exercise's supporting role in weight reduction is vital. A study at the Boston University Medical Center of overweight police officers and other public employees confirmed that those who dieted without exercise regained almost all their old weight, while those who worked exercise into their daily routine maintained their new weight. 　 If you have been sedentary (极少活动的) and decide to start walking one mile a day, the added exercise could burn an extra 100 calories daily. In a year's time, assuming no increase in food intake, you could lose ten pounds. By increasing the distance of your walks gradually and 　making other dietary adjustments, you may lose even more weight. 16. What is said about the average American in the passage? A) They usually ignore the effect of exercise on losing weight. B) They prefer "light" beer and low-calorie bread to other drinks and food. C) They know the factors that play a positive role in keeping down body weight. D) They tend to exaggerate(夸大) the healthful effect of "light" beer. 17. Some people dislike exercise because_______. A) they find it hard to exercise while on a diet

B) they don't think it possible to walk 3 miles every day C) they think it is physically exhausting

D) they find consulting caloric-expenditure charts troublesome 18. "Even exercise professionals concede half a point here" (Line 3, Para. 2) means "They

_____”. A) are not fully convinced that dieting can help maintain one's new weight B) agree that the calories in a small piece of pastry can be difficult to work off by exercise C) are not sufficiently informed of the positive role of exercise in losing weight D) partially believe diet plays a supporting role in weight reduction 19. What was confirmed by the Boston University Medical Center's study? A) Weight reduction is impossible without exercise. B) Even occasional exercise can help reduce weight. C) Controlling one's calorie intake is more important than doing exercise. D) One could lose ten pounds in a year's time if there's no increase in food intake. 20. What is the author's purpose in writing this article? A) To stress the importance of maintaining proper weight. B) To support the statement made by York Onnen. D) To show the most effective way to lose weight. D) To justify the study of the Boston University Medical Center.

议论文：1推断题 2细节题 3猜测词义 4推断题 5主旨题　 (ACDAC)

4. Which of the following sentences is not true according to the passage?

　 A. In fact, glasses or dishes used for packaging do not cost money at all.

　 B. “Family Size” printed on the package means that he is rather economic.

　 C. To a child, even to an adult, the form is far more important than the content.

　 D. Words and pictures written on the package are thought to be an advertisement.

3.What suggestion does the author give in the passage?

　 A. It’s not good to buy the product which is sold in a glass or dish

　 B. The quality of a container has nothing to do with the quality of the product.

　 C. The best choice for a buyer is to buy a product in a plain package

　 D. A buyer should buy what he needs most rather than a well-designed package

2. From the passage we know the buyer pays more attention to ________.

　 A. the size of a container　 B. a container with attractive pictures

　 C. a well-designed container　 D. a plain container with low cost

1. “A buyer will get something for nothing” in Paragraph 3 most means that ______.

　 A. a buyer will not get what he pays for

　 B. a buy will get more than what he pays for

　 C. a buyer will get something useful free of charge

　 D. a buyer will get more but pay less