填入下面文段空白处的词语，最恰当的一组是（    ）

    有的人在填报高考志愿时选报热门专业，理由是能学以致用，   ①    是一种误解。学以致用的真正含义是将学到的知识用于实践，   ②   不是看什么东西有用才决定去学。屏弃功利性    ③    使人抱着乐观的态度去学习；   ④   有用才去学习会使人产生心理负担，    ⑤    总要担心以后会不会真的有用。抱着功利之心去挑选专业，往往会牺牲自己真正的 兴趣，     ⑥     毕业后谋到了不错的职位，也不一定就工作得很开心。

把300千克苹果分装在大、小两种盒子里，大盒能装40千克，小盒能装15千克，至少需要____ 个大盒和____ 个小盒．（每盒都装满）

                                                               Saying no starts small
    'All right then-just one more piece…' Words every girl has said when they are faced with the delicious cheesecake. Of course, many of us know we may eat the whole thing in the end.
    It isn't just girls. Most of us find it hard to say 'no' to something attractive, However, scientists now say that willpower is very important to success and a happy life.
    Scientists in different countries have been studying the effects of willpower on people's lives for a long time. The results are similar, according to an article on February 7 in the Guardian, a famous British newspaper.
    In one experiment, scientists told young children that they could either have a marshmallow(圆形软糖) now, or two marshmallows in 15 minutes. Waiting obviously needed more willpower. Scientists then continued studying the children as they grew up. They wanted to see if some children always had stronger willpower. They also wanted to see how having stronger willpower affected their lives.
    Years later, scientists found that the children who had waited for two marshmallows were all healthier, happier and richer adults. Oppositely, the children who had shown weaker willpower at that young age were more likely to be in low-paid jobs, to be overweight, to have social problems.
    But there is hope, Roy F Baumeister, an American social psychology(心理学) professor(教授) told the Guardian. Baumeister says we can train our willpower just like we train our muscles.  Even a little practice can strengthen our overall self-control if we do it regularly.
    You could start by making yourself stand up straight, speaking in complete sentences, or using a computer mouse with the other hand. Scientists have found that people who manage to change little habits often perform much better in laboratory willpower tests.
    Like muscles, willpower can 'get tired'. Don't try to do too many things at the same time, or when you don't have enough energy, for example when you are ill.  If you already feel tired, you can try to recharge(恢复) your willpower with a good night's sleep and by eating well.