One of the most common dangers to climbers is altitude sickness, which can affect even very experienced climbers.
出自-2012年12月听力原文
Altitude sickness usually begins when a climber goes above 8000 or 9000 feet
出自-2012年12月听力原文
Besides these symptoms of altitude sickness, others such as headache and fatigue may also occur.
出自-2012年12月听力原文