感觉这道题B，C都对啊，答案是B，请牛人讲解一下吧～～～谢谢

29.The price of a full-fare coach ticket from Toronto to Dallas on Breezeway Airlines is the same today as it was a year ago, if inflation is taken into account by calculating prices in constant dollars. However, today 90 percent of the Toronto-to-Dallas coach tickets that Breezeway sells are discount tickets and only 10 percent are full-fare tickets, whereas a year ago half were discount tickets and half were full-fare tickets. Therefore, on average, people pay less today in constant dollars for a Breezeway Toronto-to-Dallas coach ticket than they did a year ago.

Which one of the following, if assumed, would allow the conclusion above to be properly drawn?

(A) A Toronto-to-Dallas full-fare coach ticket on Breezeway Airlines provides ticket-holders with a lower level of service today than such a ticket provided a year ago.

(B) A Toronto-to-Dallas discount coach ticket on Breezeway Airlines costs about the same in constant dollars as they did a year ago.

(C) All full-fare coach tickets on Breezeway Airlines cost the same in constant dollars as they did a year ago.

(D) The average number of coach passengers per flight that Breezeway Airlines carries from Toronto to Dallas today is higher than the average number per flight a year ago.

(E) The criteria that Breezeway Airlines uses for permitting passengers to buy discount coach tickets on the Toronto-to-Dallas route are different today than they were a year ago.

原价一样，现在90%是打折机票，10%是原价

以前50%的打折机票，50%原价

得出结论：现在做飞机便宜

前提，打折的幅度要一样啊，要是一个打一折，一个打9折，那就两说了。

C说全价票和去年一样，这文章已经说了，不是文章的前提

 says all full fare ticket on the airline. The term all refers to other routes

that are not Toronto to Dallas. Thus C is incorrect.

原来一直受inflation和constant dollars的影响，参不透。

现在终于想明白了。

inflation是一个考虑因素，inflation即用一样的钱，能买到的东西少了。

B选项，折后价算成的dollar和一年前是一样的，也就是说票价便宜了。