已知点P（x,y)在不等式组$\left\{\begin{array}{c}x-2\le 0\\ y-1\le 0\\ x+2y-2\ge 0\end{array}\begin{array}{c}\\ \end{array}\right.$表示的平面区域上运动，则z=x-y的取值范围是　(     ) 

下列有关生物遗传和变异叙述正确的是（　　）

阅读国风《生命的品格》，完成下列各题。

      ①生命是有限的，从一定意义上说，我们无法把生命延长到我们理想的程度，那我们所能做的就只有如何提高这有限生命的质量，使这有限的人生旅途更有意义。

      ②要懂得珍惜。珍惜每一寸光阴。要把有限的时间花在有意义的事情上。花在学习上，多读一点书，多学一点东西，多了解一点世界。少壮不努力，老大徒伤悲。花在工作上，多做一些有益于社会的事情。当我们离开这个世界时，真正做到不因虚度年华而悔恨。要珍惜一粒米、一寸布、一张纸、一支铅笔。“一粥一饭，当思来之不易；半丝半缕，恒念物力维艰。”我们享受的每一份服务，我们使用的每一件物品，都凝聚着多少人辛勤劳动的汗水。我们吃饭时只看到雪白的大米，却看不到农民在烈日的暴晒下赤脚在泥水田里耕种；我们用精美的铅笔学习写字，却不知道制造一根铅笔从伐木工人到油漆包装送到文具店，要经过多少人的劳动。要珍惜朋友之间的友谊。人海茫茫，能回首相聚是缘分。要珍惜别人对自己的每一份关爱，哪怕是一个招呼、一个微笑，滴水之恩，当涌泉相报。

      ③要有悲悯情怀。人生在世，要有一颗感恩的心。小时候，我们离不开别人的养育，吃着母亲的奶水长大；长大了，也离不开别人的帮助，吃着别人生产的粮食，穿着别人缝制的衣服，住着别人建造的房子；生病了，还要别人照顾，也是别人教我们读书写字。我们的每一步，都离不开别人。所以，要尊重别人，包容别人，常怀一颗慈悲的心去帮助别人。帮助了别人，自己的心灵也会得到慰藉，境界也会得到升华；“赠人玫瑰，手留余香。”

      ④要有面对困难的意志和勇气。人一生下来的啼哭就预示着人生就要经历种种磨难。关键是要有敢于面对苦难，有直面苦难的信心和勇气。当一个人从不计较受到了磨难，忍受磨难就不是一种惩罚，而是一件快乐的事。有时候，通过忍受磨难，才能表达真理和爱，才能唤醒人性中的良知。一个人只有敢于并勇于承受磨难，才能不断锻炼成无所不克的意志，才能不断增长道德勇气，以至可以无谓地直面死亡。孟子说：“天将降大任于是人也，必先苦其心志，劳其筋骨，饿其体肤”，说的也是这个意思。

      ⑤人世间，我们每个人都是匆匆过客，都是一个行者，沿途的风景再好，你只能尽情地看，但不能带走；路上的客店再舒适，但你只是一个异客，不是属于你的。所以，要有一个明白头脑，把人生想透彻。在滚滚红尘中，要学会“爱惜自己的羽毛”，从而自始至终干干净净地做人，走完人生的旅程，这就是生命的品格。

云南省文山市是我国特有名贵中药材田七的主产地，云南省有“动植物王国”的美誉，其原因是（    ）

①纬度低，热量充足； ②地形崎岖，垂直差异显著； ③黑土广布，土壤肥沃；  ④开发晚，保护得当；

    If you work hard to have a positive attitude, you might be surprised by how much better you feel about yourself and life in general. ____ The less stress you feel, the better you will feel generally. So if you've been feeling tired, think about the good, put on a happy face and you just might feel better soon.

    But how can you have a positive attitude when life is hard? It's more than just turning life's lemons into lemonade. ____ But it's worth it. Here are some ways you can develop and maintain(保持)a positive attitude even in the midst of life's troubles.

    ____It just means being an optimist and looking for the good in things, rather than being a pessimist(悲观者) and focusing on the bad in things. Sometimes your view can make all the difference in the world.

    Identify(确认) those areas of your life that might not be going so well. ____ Focus on one area at a time and think of ways you can find the positive in them.

    Smile and laugh! Yes, it can be that simple. Learn to love life, no matter what's going on. Smile at others and they will smile back at you.____Sometimes laughter really is the best medicine.

    Exercise！Get off the couch and get moving. Being active and healthy can give you a completely different attitude to life.

A. Have fun and find the humor in life.

B. You may find it hard to stay positive in your life.

C. Having a positive attitude can take some hard work.

D. A positive attitude doesn't mean taking no notice of life's troubles.

E. Having a positive attitude can also reduce your stress level.

F. These are the areas likely to make you think negative thoughts.

G. Go to bed earlier so you get the sleep you need to feel positive.