It was a boring and dull afternoon．Olivia had to work on a project for school about invention with wheels．

    She couldn't think of any ideas．

    "What am I going to write，Eliza？"she asked her little sister．Eliza didn't answer．

    "I'm going to go for a bicycle ride．That will help me think．"

    Eliza followed her．

    Go inside，Eliza．Tell Mom I'll be back soon．"

    Eliza was an obedient four﹣year﹣old girl．She always listened to Olivia．

    "Be a good girl，Eliza．"Olivia closed the gate and rode away．She didn't see the gate swing（摇摆） open behind her．

    Olivia went riding fast down the hill from her house．It was exciting to move so quickly．She was slowing down to make a turn when she saw someone behind her．

    "Eliza!You are following me the whole time!You didn't listen!And I must have forgotten to lock the gate!"

    Then she saw that Eliza was crying and walking difficultly with a wounded knee．

    "I fell down，"said Eliza．"My knee hurts!""Oh，no!You won't be able to get up that hill!"

    Olivia knew it was foolish to leave her sister alone outside．What were they going to do？Olivia started to get scared，but she knew she must be brave and find a way to get home．Then she saw an old wooden carriage by the path．The carriage was so old that it was broken when she picked it up，but the four metal wheels and two axles （车轴） were still strong．Then she found an old straw mat （垫子） and some strong wire．She tied the mat between the two axles with the wire．Then she tied the new cart to the back of her bike seat．

    "Come on，Eliza!Get on the cart．"

    Olivia got on her bicycle and started to ride．It was hard to get up the hill，but she decided to get home．Finally，they arrived．

    "We're home，"said Olivia．"And I have an idea for my wheel project．I'm going to write about my new invention﹣a little sister carrier!"

天舟瘦身记

    ①我是太空“快递小哥”﹣﹣天舟一号货运飞船。最近我承接了一项艰巨又光荣的运输任务。从位于海南岛的中国文昌航天发射场出发，我将穿透厚厚的大气层，把货物送到“客户”﹣﹣天宫二号空间实验室里。

    ②我送去的货物______有各种太空实验设备，_________维持天宫二号运行的补给。而我的“车”﹣﹣运载火箭的运载能力是固定的，如果想运更多的货物，我就必须在保证自己足够强壮的同时，尽可能再不断减肥，把瘦下来的重量，替换成更多的货物。

    ③谈到“减肥”，恐怕对很多人都是个头疼的问题。不过好在我有一个厉害的私人教练﹣﹣中国航天科技集团公司五院的研制人员。他们给我做了全面检查，并为我量身定制了多种减肥和健身方案。

    ④减过肥的人都知道，腰部赘肉是最难减下去的。我的腰部是一个个连接框，为了将我高大的身躯牢固连接，这些连接框做得很厚实，所以显得臃肿，减肥的第一步就是减腰部赘肉。

    ⑤经过多次试验验证，他们将我的连接框设计成镂空形式，通过数控加工仿真技术，去除非受力部分的“肉肉”。只保留结构受力部分。现在我腰部每个连接框的重量都降低到原来的50%左右，但却丝毫没有影响我的结实程度。

    ⑥我的教练十分严格，不仅不放过肉眼可见的腰部赘肉，连肉眼几乎无法分辨的“皮下脂肪”也不放过。我的外部是一种壁板结构，壁板连接完成后，组成的密封空间就是装货物的肚子了。虽然壁板厚度只有不到3毫米，但是在“教练”看来，依然有减重的空间。他们严格控制加工温度、切削速度等参数，尽量使壁板厚度贴近设计人员给出的公差下限。也就是在不影响性能的基础上，通过这种“皮下脂肪去除法”，尽可能让壁板变薄。由于壁板面积很大，即使去除A4纸那样薄的一层“脂肪”，整舱的重量也会下降很多。这不，在研制人员的努力下，我的体重因此又减少了30千克左右。减去的这些重量，又够我多运送好几台设备呢。

    ⑦为了装下更多的货物，设计人员用货架将我的肚子分成了许多区域。我的“教练”连这些货架也没放过，他们选用了轻质高强度材料组成货架。比如，“货架面板”﹣﹣仪器板，使用的是铝合金蜂窝板；“货架框架”﹣﹣立梁，使用的是碳纤维材料。每一项改进都涉及多种先进而复杂的制造工艺。为此，研制人员完成了许多工艺攻关，还采用了“无应力”装配的方式，保证了货架装配误差不超过2毫米。这些“锻炼”让我的肌肉又轻又强壮，保证能将货物完好无缺地交给天宫二号。

    ⑧在教练的魔鬼训练下，我的瘦身计划圆满完成。经过体检，各项指标均已到达要求。不多说了，我已经装满货物整装待发了。天宫二号，我来啦！

我们与父母进行有效沟通的关键和结果分别是（   ）