28. In the second paragraph, the author implies that using radio transmitters would allow a researcher who studies crow to (A) identify individual crows

　　(B) follow flocks of crows over long distances

　　(C) record the times when crows are most active

　　(D) help crows that become sick or injured

　　29. According to the third paragraph, which of the following is true about crows?

　　(A) They seldom live in any one place for very long.

　　(B) They thrive in a wide variety of environments.

　　(C) They have marked preferences for certain kinds of foods.

　　(D) They use up the resources in one area before moving to another.

　　30. In line 19,the word "inclinations" is closest in meaning to

　　(A) tricks

　　(B) opportunities

　　(C) preferences

　　(D) experiences

　　31. In lines 19-21, the author mentions a pet crow to illustrate which of the following? (A) The clever ways that crows solve problems

　　(B) The differences between pet crows and wild crows

　　(C) The ease with which crows can be tamed

　　(D) The affection that crows show to other creatures

　　32. Which of the following statements is supported by the passage?

　　(A) Crows have relatively long lives.

　　(B) Crows have keen vision

　　(C) Crows are usually solitary

　　(D) Crows are very intelligent.

　　QUESTIONS 33-41

　　�牐營(yíng)n the early days of the United States, postal charges were paid by the recipient and

　　Charges varied with the distance carried. In 1825, the United States Congress permitted

　　local postmasters to give letters to mail carriers for home delivery, but these carriers

　　received no government salary and their entire compensation depended on what they

　　were paid by the recipients of individual letters.

　�。牐營(yíng)n 1847 the United States Post Office Department adopted the idea of a postage stamp,

　　which of course simplified the payment for postal service but caused grumbling by

　　those who did not like to prepay. Besides, the stamp covered only delivery to the post

　　office and did not include carrying it to a private address. In Philadelphia, for example,

　　with a population of 150,000, people still had to go to the post office to get their mail.

　　The confusion and congestion of individual citizens looking for their letters was itself

　　enough to discourage use of the mail. It is no wonder that, during the years of these

　　cumbersome arrangements, private letter-carrying and express businesses developed.

　　Although their activities were only semilegal, they thrived, and actually advertised that

　　between Boston and Philadelphia they were a half-day speedier than the government

　　mail. The government postal service lost volume to private competition and was not

　　able to handle efficiently even the business it had.

　�。牐燜inally, in 1863, Congress provided that the mail carriers who delivered the mail

　　from the post offices to private addresses should receive a government salary, and that

　　there should be no extra charge for that delivery. But this delivery service was at first

　　confined to cities, and free home delivery became a mark of urbanism. As late as 1887,

　　a town had to have 10,000 people to be eligible for free home delivery. In 1890, of the

　　75 million people in the United States, fewer than 20 million had mail delivered free

　　to their doors. Th e rest, nearly three-quarters of the population, still received no mail

　　unless they went to their post office.