请阅读  Passage 1,完成第  21~25小题 。

Passage 1

First two hours, now three hours-this ishow far in advance authorities are recommending people show up to catch adomestic flight, at least at some major U.S. airports with increasingly massivesecurity lines.

Americans are willing to toleratetime-consuming security procedures in return for increased safety. The crash ofEgyptAir Flight 804, which terrorists may have downed over the Mediterranean Sea,provides another tragic reminder of why. But demanding too much of airtravelers or providing too little security in return undermines public supportfor the process. And it should: Wasted time is a drag on Americans ' economicand private lives, not to mention infuriating.

Last year, the Transportation SecurityAdministration (TSA) found in a secret check that undercover investigators wereable to sneak weapons-both fake and real-past airport security nearly everytime they tried. Enhanced security measures since then, combined with a rise inairline travel due to the improving economy and low oil prices, have resultedin long waits at major airports such as Chicago ' s O ' Hare International. Itis not yet clear how much more effective airline security has become-but thelines are obvious.

Part of the issue is that the governmentdid not anticipate the steep increase in airline travel, so the TSA is nowrushing to get new screeners on the line. Part of the issue is that airportshave only so much room for screening lanes. Another factor may be that morepeople are trying to overpack their carry-on bags to avoid checked-baggagefees, though the airlines strongly dispute this.

There is one step the TSA could take thatwould not require remodeling airports or rushing to hire: Enroll more people inthe PreCheck program. PreCheck is supposed to be a win-win for travelers andthe TSA. Passengers who pass a background check are eligible to use expectedscreening lanes. This allows the TSA to focus. on travelers who are higherrisk, saving time for everyone involved. The TSA wants to enroll 25 millionpeople in PreCheck.

Ithas not gotten anywhere close to that, and one big reason is sticker shock:Passengers must pay $85 every five years to process their background checks.Since the beginning, this price tag has been PreCheck ' s fatal flaw. Upcomingreforms might bring the price to a more reasonable level. But Congress shouldlook into doing so directly, by helping to finance PreCheck enrollment or tocut costs in other ways.

Which of the following contributes to long waits at major airports?