$ 16,800 is the collector's value of ______. A. the One Penny Orange-Red B. a corr
$ 16,800 is the collector's value of ______.
A. the One Penny Orange-Red
B. a correctly printed'1847 stamp
C. the Two Penny Blue
D. both A and C
$ 16,800 is the collector's value of ______.
A. the One Penny Orange-Red
B. a correctly printed'1847 stamp
C. the Two Penny Blue
D. both A and C
A.航空运费到付
B.航空运费预付
C.其他费用到付
D.其他费用预付
数据集NBASAL.RAW包含了美国篮球协会(NBA)269位运动员的薪水信息和职业统计。
(i)估计一个将每场得分(points)与加入联盟年数(exper)、年龄(age)、大学期间打球年数(coll)相联系的模型。包含一个exper的二次项,其他变量都应该以水平值形式加入模型。按照通常的格式报告结果。
(ii)保持大学打球年数和年龄不变,从加入联盟的第几个年份开始,在NBA打球的经历实际上将降低每场得分?这讲得通吗?
(iii)你为什么认为coll具有负系数,而且统计显著?(提示:NBA运动员在读完大学之前被选拔出,甚至直接从高中选出。)
(iv)有必要在方程中增加age的二次项吗?一旦控制了exper和coll之后,这对年龄效应意味着什么?
(v)现在将log(wage)对points,exper,exper2,age和coll回归。以通常的格式报告结论。
(vi)在第(v)部分的回归中检验age和coll是否联合显著。一旦控制了得分和资历,这对考察年龄和受教育程度是否对工资具有单独影响这个问题有何含义?
How can a single postage stamp be worth $ 16,800?
Any mistake made in the printing of a stamp raises its value to stamp collectors. A mistake on one in expensive' postage stamp has made the stamp worth a million and a half times its original value.
The mistake was made more than a hundred years ago in the British colony of Mauritius, a small is land in the Indian Ocean. In 1847 an order for stamps was sent to a London printer, and Mauritius was to become the fourth country in the world to issue stamps.
Before the order was filled and delivered, a ball (舞会) was planned at Mauritius' Government House, and stamps were needed to send out the invitations. A local printer was instructed to copy the de sign for the stamps. He accidentally inscribed the words "Post Office" instead of "Post Paid" on the sever al hundred stamps that he printed.
Today there are only twenty-six of these misprinted stamps left--fourteen "One Penny Orange-Reds" and twelve "Two Penny Blues". Because of the Two Penny Blue's rareness (罕见) and age, collectors have paid as much as $ 16,800 for it.
A postage stamp's value to collectors is raised if ______.
A.there are few others like it
B.there are no errors on the stamps
C.a mistake is made in the ,printing
D.both A and C
A. was an independent country
B. was a smail island in the Pacific Ocean
C. belonged to India
D. was one of the British colonies
Passage Two
Started in 1636, Harvard University is the oldest of all the many colleges and universities in the United States. Yale, Princeton, Columbia and Dartmouth were opened soon after Harvard.
In the early years, these schools were much alike. Only young men went to college. All the students studied the same subjects, and everyone learned Latin, Greek and Hebrew. Little was known about science then, and one kind of school could teach everything that was known about the world. When the students graduated, most of them became ministers (大臣) or teachers.
In 1782, Harvard started a medical school for young men who wanted to become doctors. Later, lawyers could receive their training in Harvard's law school. In 1825, besides Latin and Greek, Harvard began teaching modern languages, such as French and German. Soon it began teaching American history.
As knowledge increased, Harvard and other colleges began to teach many new subjects. Students were allowed to choose the subjects that interested them.
Today, there are many different kinds of colleges and universities. Most of them are made up of smaller schools that deal with (涉及) special fields of learning. There's so much to learn that one kind of school can't offer it all.
36. The oldest university in the US is______.
A. Yale
B. Princeton
C. Harvard
D. Columbia