题干

科学家找到火星上有水的决定性证据:

据美国宇航局喷气推进实验室(JPL)官方网站报道,美国宇航局的好奇号火星车所做的考察显示火星盖尔陨坑内的夏普山(Mount Sharp)是由一个大型湖泊环境中层层沉积层叠加而成,中间可能经过了长达数千万年的时间.

那么为何研究人员会对这座位于一个陨坑内遍布沉积岩的山如此感兴趣?夏普山高大约3英里(5000米),其山麓地区出露有数百层的沉积岩露头.这些岩层显示不同的环境相相互交错叠加﹣﹣湖泊相,河流相以及风成沉积相,它们都见证了一个远比此前所知任何案例中都更大,持续存在时间更长的湖泊水位的反复涨落和蒸发轮回.

火星上曾有过液态水对于科学家来说主要有两点意义:其一,火星上可能曾经存在过生命;其二,火星可以改造成人类的另一个家园.

就人类目前掌握的情况看,液态水是生命存在必不可少的条件.请依据为你提供的实验材料,设计一个实验,能证明液态水可以影响生物的生存.

实验材料:培养皿两套,恒温箱一个,玉米种子若干,清水若干,过滤纸若干,等.

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    My best friend Jenny and I got to the mall for shopping.She held up a white sweater and matching skirt.“Do you like this?”she asked.

    “It's great,''I said.Jenny nodded and continued looking while I moved about.touching the beautiful clothes.“ I'll try this on.”Jenny walked towards the dressing room.After a while,she came out in the outfit(一套衣服).She looked beautiful.

    I sighed. Part of me wanted to say how good she looked, but another part stopped the words coming out.Jenny was in such good shape that she'd look good in the outfit.Sometimes, I regretted choosing a best friend who was so pretty.God,why can't I be the one with the rich parents and the great look?More and more, I was envious(妒忌的)of her.

    “Well,Teresa,what do you think?”Jenny asked more than once.“Do you like it?''

    The outfit looked great on her,but I lied,“Not really.I think you need something with more colors.''

    “You think so?"Jenny said doubtfully.

    “Just believe me.We'll find something better,"I told her,pushing her back into the dressing room.“You just can't buy the first thing you see.”I did my best to get Jenny out of the store,away from that outfit.As we left,Jenny gave the sweater one last look.

    Just down the mall,we passed a yogurt place."My treat,''Jenny said,pulling out her wallet.

    I could never say no to chocolate,so we got some and sat down at a table.As Jenny talked without stopping about a million things,I thought about my feelings toward her.Those feelings weren't kind.

    Sitting there,  ▲  Jenny was attractive(吸引人的)not just because of her good luck,but more because of her kindness.Treating me to chocolate was far from her only show of generosity.She also let me drive her car and borrow her colothes.

    Finishing our chocolate,we headed for the next clothing store. "Look at that red sweater.''Jenny said as we passed the window."It would be perfect for you.Soon maybe you'll have enough by saving your babysitting money to buy something like that.”

    A few minutes earlier,all I had heard was about saving my babysitting money.I had hated the fact that Jenny could ask her parents for anything,and they'd buy it for her.This time,though.I heard more.I heard the voice of someone who loved and cared me for who I was.I needed to express the same to her.