9. It has been argued that the consumer has benefited from agricultural technology in the United States. Consumers are spending, on the average, a decreasing proportion of their income on food. But the demand for food, especially in prosperous countries, is virtually insensitive to income, so that as real incomes rise, the amount spent of food becomes a smaller proportion of expenditure. Therefore, in order to judge whether consumers have really benefited from agricultural technology, it is necessary to know whether ____________.
    Which of the following is the most logical completion of the passage above?
    (A) incomes will continue to rise考试论坛
    (B) the proportion of income spent on food has declined more sharply than rises in real income warrant
    (C) technological costs constitute a substantial portion of the cost of food production
    (D) the quantity of food produced by American farmers has increased
    (E) consumers will increase the proportion of their income spent on foot as food prices rise
    Questions 10-15
    Four couples, the Bascos, the Jeffersons, the Pardas, and the Roberts, are learning a new dance. The dancers must perform this dance in pairs. At the beginning of the dance, each of the married couples is such a pair, but there are three calls for partner changes-calls X, Y, and Z-with the following results:
    When call X is made, Mr. Basco and Mr. Parda exchange partners.
    When call Y is made, Mrs. Roberts and Mrs. Jefferson exchange partners.
    When call Z is make, Mr. Jefferson and Mr. Parda exchange partners.
    When more than one call is made, each change of partners is based on the arrangement of partners produced by the preceding call. *
    10. If, since beginning of the dance, there has been one partner change, made in response to call X, which of the following must be a pair of partners?
    (A) Mr. Basco and Mrs. Parda
    (B) Mr. Basco and Mrs. Roberts
    (C) Mr. Jefferson and Mrs. Parda
    (D) Mr. Jefferson and Mrs. Basco
    (E) Mr. Roberts and Mrs. Jefferson
    11. If, after the first two calls of the dance, each dancer is again partnered with his or her own spouse, the calls made could have been
    (A) X followed by Y
    (B) Z followed by X
    (C) X followed by X, or Y followed by Y, or Z followed by Z
    (D) X followed by X, or Y followed by Y, but not Z followed by Z
    (E) X followed by X, or Z followed by Z, but not Y followed by Y
    12. If, since the beginning of the dance, two partner changes have been made, the first in response to call X and the second in response to call Y, which of the following must be true?
    (A) Mrs. Basco is partnered with Mr. Roberts.
    (B) Mrs. Jefferson is partnered with Mr. Jefferson.
    (C) Mr. Parda is partnered with Mrs. Roberts.
    (D) Only two of the women are partnered with their husbands.
    (E) No man is partnered with his wife.
    13. If Mr. Basco is partnered with Mrs. Basco after the first two calls of the dance, and if the second call was Y, which of the following is true of the first call?
    (A) It must have been X.
    (B) It must have been Y.
    (C) It must have been Z
    (D) It could have been any of the three calls except X.
    (E) It could have been any of the three calls except Z.
    14. If Mr. Jefferson is partnered with Mrs. Basco after the first two calls of the dance, and if the second call was Z, which of the following is true of the first call?
    (A) It must have been X.
    (B) It must have been Y.
    (C) It must have been Z.
    (D) It could have been any of the three calls except Y.
    (E) IT could have been any of the three calls except Z.
    15. If the dance begins with the three calls Z, X, and Y, in the order given, it must be true that after the third call.
    (A) Mr. Parda partners Mrs. Jefferson
    (B) Mr. Parda partners Mrs. Roberts
    (C) Mr. Basco partners Mrs. Basco
    (D) Mr. Basco partners Mrs. Jefferson
    (E) Mr. Basco partners Mrs. Roberts