68．Why does the writer say “all Americans are on the move” in the passage?
    A．Americans like to travel on Christmas.
    B．Because American has a lot of earthquakes on every Christmas.
    C．Because Americans don’t go sleep on Christmas Eve.
    D．Because Christmas holidays are the busiest times of the year.

                                    D
Avalanche
    Death comes quickly in the mountains. Each winter holidaymakers are caught unawares as they happily ski away from the fixed runs,little realizing that a small avalanche can send them crashing in a bone-breaking fall down the slope and leave them buried under tons of crisp white snow. There are lots of theories about how to avoid disaster when hit by an avalanche. Practice is normally less cheerful.
The snow in the Salzburg of Austria where a recent disaster took place was typical avalanche material. For several days before the incident I had skied locally. Early winter snow was wearing thin and covered with ice. On top of that new, warmer flakes were gently falling to produce a dangerous carpet. To the skier who enjoys unmarked slopes it is tempting stuff, deep new power snow on a hard base---the skiing that dreams are made of. And sometimes nightmares.