1Which of the following is NOT true of working class Americans?

 A.They work long hours．  B.They live from paycheck to paycheck．  C.They don't want to be healthy eaters．  D.They want to save money for presents．  

2What does the survey indicate?

 A.Many low-income Americans want large portions．  B.Twenty percent of Americans want smaller portions．  C.Fifty-seven percent of Americans want large portions．  D.Forty-five percent of Americans want smaller portions．  

3What happened in the 1970s?

 A.The US government called on its people to reduce their weight．  B.Health experts persuaded restaurants to serve smaller portions．  C.The United States produced more grain than needed  D.The American waistline started to expand  

4Why do American restaurants serve large portions?

 A.Because Americans associate quantity with value  B.Because Americans have big bellies．  C.Because Americans are good eaters．  D.Because Americans are too weak．  

5Parents in the United States tend to ask their children

 A.to save food for tomorrow．  B.to wash the dishes．  C.not to waste food  D.not to eat too much．   3、（三） Sunspots It's not surprising that sunspots（太阳黑子）were observed by ancient astronomers（天文学家）．The largest sunspots on the sun can be seen without a telescope．1t was not until the invention of the telescope（望远镜）in the early l7th century，however，that systematic studies of sunspots could be undertaken．The great astronomer Galileo was among the first to make telescopic observations of sunspots．Sunspots are regions of extremely strong magnetic fields（磁场）found on the sun's surface．A sunspot has a dark central core known as the umbra．The umbra is surrounded by a dark ring called the penumbra．where the magnetic field spreads outward．Sunspots appear dark because they are giving off less radiation．They are cooler than the rest of the sun's surface．Sunspots are frequently observed in pairs or in paired groups．The members of a spot pair are identified as the leading spot and the following spot．They are identified by their position In the pair In terms of the direction in which the sun rotates（旋转）．The number of sunspots at any one time varies．A large spot group may consist of as many as 10 groups and 300 spots across the sun．The number of spots changes in a fairly regular pattern called the sunspot cycle．The largest number occurs about every 1 years．At sunspot minimum, there are at most just a few small spots．The average lifetime of an individual spot group is roughly one solar rotation．which is about 25 days．The most persistent large spots, however, can survive for two to three months．

1In the last paragraph the word" persistent" means

 A.important．  B.effective&n