题目内容：

Today’s travelers may explore faraway cultures and countries by booking a round-the-world (RTW) trip through a global airline alliance (联盟). If you’re planning an extended business trip, a long vacation, or a year off, an RTW airline fare may be just the ticket.

RTW tickets can be purchased in economy, business class, and sometimes first class, depending on the alliance. Ticket prices can range from approximately $2,500 to $23,000, depending on class of service, mileage, routing(路线), and number of stops. They typically average between $3,000 and $5,000, although a simple two-or-three-stop RTW ticket might cost as little as $1, 500. Booking an RTW ticket through a global airline alliance allows you to piece together routes on member airlines to create one continuous trip.

Where to begin? Here are some tips:

●Start planning at least six months in advance to ensure the routes you want are available.

●To save on costs, visit destinations in their off seasons.

●If you fly west to east, your flights will be speedier due to tailwinds.

●If you plan to travel extensively within a continent, you can combine your RTW ticket with an airline alliance’s regional travel passes.

●You can often save a significant amount by originating your RTW trip in a country outside the U.S.

The alliances have various price tiers. The SkyTeam global airline alliance, for example, allows you fly up to 26,000 miles with as many as five stopovers of 24 hours or more. Fly between 29,000 and 38,000 miles, and you can stop over up to 15 times. You can plot your journey with SkyTeam’s “Round the World” planner or call a member airline for assistance.

Sometimes RTW tickets are discounted. SkyTeam, for instance, recently offers 10% off RTW, economy- class ticket. Check SkyTeam’s website for current offerings.

1.What can we know about an RTW trip through a global airline alliance?

A. It is only intended for international trade.

B. Its price is fixed according to class of service.

C. The lowest price of an RTW ticket is $1,500.

D. Customers can choose their routes and stops.

2.Which of the following is NOT a tip recommended by the author?

A. Plan your trip in advance.

B. Never include the U.S. in your trip.

C. Visit destinations in their off seasons.

D. Combine an RTW ticket with regional travel passes.

3.The SkyTeam global airline alliance recently offers customers ________.

A. unlimited-stopover trips    B. only economy-class tickets

C. a discount on certain tickets    D. a new website for assistance