4.实验室中需要用平行光做实验，现手头上有小灯泡、凸透镜、凹透镜等，以下获得平行光的方法中正确的是(　　 )

A.将小灯泡放在凸透镜的主光轴上，光源射向凸透镜的光经凸透镜后变为平行光

B.将小灯泡放在凸透镜的焦点处，光源射向凸透镜的光经凸透镜后变为平行光

C.将小灯泡放在凹透镜的主光轴上，光源射向凹透镜的光经凹透镜后变为平行光

D.将小灯泡放在凹透镜的焦点处，光源射向凹透镜的光经凹透镜后变为平行光

3.下图中各图分别表示经过透镜后的光路图，其中正确的是(　 )

2.下图表示一条光线经过三棱镜后的光路图，其中正确的是(　 　)

1.一束平行光线照射到某透镜后，光线发散了，这个透镜一定是(　　 )

A.凸透镜　　 B.凸镜　　 C.凹透镜　　　 D.凹镜

55. What is the author trying to tell us?

A.　　　 Happiness often goes hand in hand with pain.

B.　　　 One must know how to attain happiness.

C.　　　 It is important to make commitments.

54. To understand what true happiness is one must_________________.

A.　　　 have as much fun as possible during one’s lifetime.

B.　　　 make every effort to liberate oneself from pain

C.　　　 put up with pain under all circumstances

D.　　 be able to distinguish happiness from fun

53. From the last paragraph, we learn that envy sometimes stems from__________________..

　　 A. hatred　　 B. misunderstanding　　　 C.prejudice　　 　　　 D. ignorance

52. Raising children, in the author’s opinion is ______________..

A. a moral duty　　 　　　B. a thankless job　　　

　　　 C. a rewarding task　　　　 　　　 D. a source of inevitable pain

51. According to the author, a bachelor resists marriage chiefly because_______________.

A.　　　 he is reluctant to take on family responsibilities

B.　　　 he believes that life will be more cheerful if he remains single

C.　　　 he finds more fun in dating than in marriage

D.　　 he fears it will put an end to all his fun, adventure and excitement

50. According to the passage, the value of a man can be________________.

A. found in external appearance　　　　　　　　

B.discovered through skin contacts

C.felt through frequent meetings　

D. discovered without physical contact

(C)

　 The way people hold to the belief that a fun-filled, pain free life equals happiness actually reduces their chances of ever attaining real happiness. If fun and pleasure are equal to happiness then pain must be equal to unhappiness. But in fact, the opposite is true: more often things that lead to happiness involve some pain.

　 As a result, many people avoid the very attempts that are the source of true happiness. They fear the pain inevitably brought by such things as marriage, raising children, professional achievement, religious commitment(承担的义务)，self-improvement.

　 Ask a bachelor(单身汉)why he resists marriage even though he finds dating to be less and less satisfying. If he is honest he will tell you that he is afraid of making a commitment. For commitment is in fact quite painful. The single life is filled with fun, adventure, excitement. Marriage has such moments, but they are not its most distinguishing features.

　 Couples with infant children are lucky to get a whole night’s sleep or a three-day vacation. I don’t know any parent who would choose the word “fun” to describe raising children. But couples who decide not to have children never know the joys of watching a child grow up or of playing with a grandchild.

　 Understanding and accepting that true happiness has nothing to do with fun is one of the most liberating realizations. It liberates time: now we can devote more hours to activities that can genuinely increase our happiness. It liberates money: buying that new car or those fancy clothes that will do nothing to increase our happiness now seems pointless. And it liberates us from envy: we now understand that all those who are always having so much fun actully may not be happy at all.