题干

如图是某实验小组做的“探究滑动摩擦力与哪些因素有关”的实验。

①实验中要求必须水平匀速拉动弹簧测力计,这样做的目的是:____。 ②分析甲、乙两次实验现象,可以得出的结论:____。 ③分析乙、丙两次实验现象,能否得出一个科学的结论 为什么 ____。④分析甲、丁两次实验现象,可以得出的结论:____

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    Now many young people are traveling around the world on their own, not because they have no one to travel with, but because they prefer to go alone.

     Kristina Wegscheider from California first traveled alone when she was at college and believes that it is something everyone should do at least once in their life. “It opens up your mind to new things and pushes you out of your comfort zone.” Wegscheider has visited 46 countries covering all seven continents(洲).

    In foreign countries, with no one to help you read a map, look after you if you get ill, or lend you money if your wallet is stolen. It is challenging. This is what drives young people to travel alone.It is seen as character building and a chance to prove that they can make it on their own.

    Chris Richardson decided to leave his sales job in Australia to go traveling last year.He set up a website, The Aussie Nomad, to document(记录) his adventures. He said he wished he had traveled alone earlier. “The people you meet, the places you visit, or the things you do, everything is up to you and it forces you to grow as a person,” said the 30-year-old.

    Richardson describes traveling alone like “a shot in the arm”, which “makes you a more confident person that was ready to deal with anything”. He said: “The feeling of having conquered something on my own is a major part of what drives me each day when I'm dealing with a difficult task. I walk around with my head up because I know deep down inside that nothing is impossible if you try.”

    The great 19th century explorer John Muir once said: “Only by going alone in silence can one truly get into the heart of the wilderness.