Although accidents do happen, skiers will be reasonably safe if they ________ .

Death comes quickly in the mountains. Each winter holidaymakers are caught unawares as they happily ski away from the fixed runs. Little do they realise 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. They can
avoid disaster only if they ski on the marked ski slopes. Otherwise there might be disaster. The snow in the Salzburg Area of Austria where a recent disaster took place was typical avalanche material. Early winter snow was wearing thin and covered with ice. On top of that new, warmer flakes were gently failing to produce a dangerous carpet.