“无论多忙，我都要争取在晚上11点前睡觉。”

“每天吃完晚饭出去走走，散散心。”

“在家尽可能不去想工作，放松自己。”

“睡觉前洗澡”

“睡觉前喝一瓶啤酒有助睡眠”

十二烷基磺酸钠

十二烷基三甲基溴化铵 (1231)

溴代十五烷吡啶 (PPB)

草酸

正确

错误

“无论多忙，我都要争取在晚上11点前睡觉.”

“每天吃完晚饭出去走走，散散心.”

“在家尽可能不去想工作，放松自己.”

“睡觉前洗澡.”

“睡觉前喝一杯啤酒有助于睡眠.”

Remote destinations

Too risky for some

Holidays that don't quite work

New findings

Very little real danger

Too much routine

Second-hand experiences

Available to all Activity Holidays Whether it's bungee-jumping, climbing or sky-diving, we want to test ourselves on holiday. Peter Jones tries to find out why. Risk-taking for pleasure is on the increase. Adventure activities and 'extreme' sports are becoming very popular and attracting everyone from the young and fit to people who, until recently, were more likely to prefer walking round museums at weekends. Grandmothers are white-water rafting, secretaries are bungee-jumping, and accountants are climbing cliffs. 【B1】__________ Well-planned summer expeditions to tropical locations are now fashionable for European university students. As they wander over ancient rocks or canoe past tiny villages, away from it all, it ]s quite possible to feel 'in tune with nature', a real explorer or adventurer. 【B2】__________ A whole blanch of the travel industry is now developing around controlled risks. Ordinary trippers, too, are met off a plane, strapped into rafts or boats and are given the sort of adventure that they will remember for years. They pay their money and they trust their guides, and the wetter' they get the better. Later, they buy the photograph of themselves 'risking all in the wild'. 【B3】__________ But why the fashion for taking risks, real or simulated? The point that most people make ix that city lie is tame, with little variety, and increasingly corrtroled. Physical exercise is usually restricted to aerobics in the gym on a Thursday, and a game of football or tennis in the park or a short walk at the weekend. 【B4】__________ Says Trish Malcolm, an independent tour operator: 'People want a sense of immediate achievement and the social element of shared physical experience is also important.' Other operators say that people find the usual type of breaks-such as a week on the beach-Loo slow. They say that participation in risk sports is a reflection of the restlessness in people. They are always on the go in their lives and want to keep up the momentum on holiday. 【B5】__________ But psychologists think it's even deeper than this. Culturally, we are being separated from the physical, outside world. Recent research suggests that the average person spends less and less time out of doors per day. 【B6】__________ Nature and the great outdoors are mostly encountered through wildlife films or cinema, or seen rushing past the windows of a fast car. In a society where people are continually invited to watch rather than to participate, a two-hour ride down a wild and fast- flowing river can be incredibly exciting. 【B7】__________ One psychologist believes that it is all part of our need to corrtrol nature. Because we have developed the technology to make unsinkable boats, boots that can stop us getting frostbite or rackets that allow us to survive in extreme temperatures, we are beginning to believe that nothing will harm us and that we are protected from nature. That is until nature shows us her true power in the form. of a storm, flood or avalanche. 【B1】______

先计算分布函数的具体表达式，再求导数得概率密度

直接利用积分上限函数求导公式，得到概率密度

根据分布函数没有办法求出概率密度

decreased.

increased.

stayed the same.

fallen dramatically.

mixed models are no longer used.

一定

不一定

正确

错误