20．What is the probable meaning of the underlined part “Their gaze is arrested” (in paragraph 3 ) ?

　A. They get something to look at.

　B. They can only look at one spot.

　C. Their eyes are clear.

19．Snowblindness can be avoided ________.

　A. by moving one’s gaze back and forth

　B. by walking ahead and keeping looking around

　C. by making up for the discomfort of one’s eyes

　D. by providing the eyes with something to focus on

18．When the eyes are tired, tears flow out ________.

　A. to clear the vision

　B. to make the eyes stop searching

　C. to make the vision unclear

　D. to produce more and more liquid

17．To prevent snowblindness caused by the strong light from snow, wearing glasses or not ________.

　A. depends on whether the snow is white enough

　B. makes no difference

　C. makes much difference

　D. depends on whether the snow is thick

16．Though great changes have taken place in the structure of American families, ________ .

　A. the majority of Americans still have faith in marriage

　B. the functions of marriage remain unchanged

　C. most Americans prefer a second marriage

　D. most Americans prefer to be single

E

　Many people believe the glare(炫目的光)from snow causes snowblindness. Yet, with dark glasses or not, they find themselves suffering from headaches and watering eyes, and even snowblindness ,when exposed to several hours of“ snow light”.

　The United States army has now determined that glare from snow does not cause snowblindness in troops in a snow -covered country. Rather ,a man’s eyes frequently find nothing to focus on (聚集) in a broad space of snow- covered without- grass land. So his gaze continually moves and jumps back and forth over the entire landscape in search of something to look at. Finding something, hour after hour, the eyes never stop searching and the eyeballs become tired and the eye muscles ache. Nature makes up for this discomfort by producing more and more fluid (流 体) which covers the eyeball. The fluid covers the eyeball in increasing quantity until it makes eyes difficult to see dearly, and the result is total, even though for a short time, snowblindness.

　Experiments led the Army to a simple method of overcoming this problem. Scouts(侦察兵)ahead of the troops are trained to shake snow from evergreen bushes, creating a dotted line as they cross completely snow - covered landscape. Even the scouts themselves throw lightweight, dark - colored objects ahead on which they can focus too. The men following can then see something. Their gaze is arrested. Their eyes focus on a bush and having found something to see, stop searching the snow -blanketed landscape. By focusing their attention on one object at a time. the men can cross the snow without becoming hopelessly snowblind or lost. In this way the problem of crossing a continuous white land is overcome.

15．Which of the following can be presented as the picture of today’s American families？

　A. Which types of family arrangements have become socially acceptable.

　B. A typical American family consists of only a husband and a wife.

　C. Americans prefer to have more kids than before.

　D. There are no nuclear families any more.

14．Divorced Americans ________ .

　A. prefer the way they live

　B. will most likely remarry

　C. have lost interest in marriage

　D. are the majority of people in the society

13．By calling Americans a marrying people the writer means that ________.

　A. Americans are more traditional than Europeans

　B. Americans expect more out of marriage than Europeans

　C. there are more married couples in the USA than in Europe

　D. more of Americans, as compared with Europeans, prefer marriage and they accept it at a younger age

12．Which is the most suitable title for the passage?

　A. The Successful Launching of “Shenzhou Ⅳ ”.

　B. The Landing of “Shenzhou Ⅳ ”.

　C. Chin a’s Manned Flight Programme.

　D. The Third Country Sending a Person into Outer Space.

D

　More surprising, perhaps, than the current difficulties of traditional marriage is the fact that marriage itself is alive and thriving(旺盛的). As Skolnich notes, Americans are a marrying people: relative to Europeans, more of us marry and we marry at a younger age. Moreover, after a decline(衰退)in the early 1970s, the rate of marriage in the United States is now increasing. Even the divorce(离婚)rate needs to be taken in this pro- marriage context: some 80 percent of divorced individuals remarry. Thus, marriage remains by far the preferred way of life for the vast majority of the people in our society.

　What has changed more than marriage is the nuclear family. Twenty- five years ago, the typical American family consisted of the husband, the wife, and two or three children. Now, there are many marriages in which couples have decided not to have any children, and there are many marriages where at least some of the children are from the wife’s previous marriage, or the husband’s, or both. Sometimes these children spend all of their time with one parent from the former marriage; sometimes they are shared between the two former spouses (配偶)．

　Thus, one can find every type of tamely arrangement. There are marriages without children; marriages with children from only the present marriages; marriages with “full - time” children from both the present and former marriages; marriages with“full- time”children from the present marriage and“ part- time”children from former marriages. There are stepfathers, stepmothers, half- brothers and half - sisters. It is not all that unusual for a child to have four parents and eight grandparents! These are enormous changes from the traditional nuclear family. But even so, even in the midst of all this, there remains one constant: most Americans spend most of their adult lives married.

11．As a matter of fact, ________ .

　A. “Shenzhou Ⅴ ”has been launched

　B. “Shenzhou Ⅳ” was a manned spacecraft

　C. “Shenzhou Ⅲ ”and“ Shenzhou Ⅳ” were not launched in the same year

　D. the dream of man flying into outer space has come true in China