在下面一段文字①②③处补写恰当的语句，使整段文字语意完整连贯，内容贴切，逻辑严密。每处不超过15个字。

沙漠不见了，地球上的生态系统是不是该长长地松口气了?没那么简单，新的问题会出现。树木虽然优点很多，比如能涵养水源，能调节气候，还可以降低噪音，①                。它们在捕获和吸收阳光的同时，还会将热量传输到空气中，以便自身降温，但这样会使得地面温度升高。树木本身虽然可以通过吸收二氧化碳而抵消掉向空气中散发的热量，可是整个过程极为缓慢，要花数十年的时间。由于有了沙漠，②             ，因为它反射阳光的能力较强，有助于散热，③           。

She ________ a dictionary to our classroom, but I did.

                                                               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.