对以下物体运动的描述（如加线的字），选择地面为参照物的是（ ）
A．月亮在白云中穿行
B．地球绕太阳公转
C．坐在奔驰的火车里
D．静靠在运行中的列车座椅上的乘客
A、月亮在白云中穿行，研究对象是月亮，“穿行”说明月亮在运动，选择的参照物是白云，不符合题意；
B、地球绕太阳公转，研究对象是地球，“公转”说明地球在运动，选择的参照物是太阳，不符合题意；
C、坐在奔驰的火车里，研究的对象是火车，“奔驰”说明火车在运动，选择的参照物是地面，符合题意；
D、静靠在运行中的列车座椅上的乘客，研究对象是乘客，“静靠”说明乘客在静止，选择的参照物是座椅，不符合题意．
故选C．
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| Last weekend, I helped my friend Alex get money for poor children at Crossroads Mall. He 1 needed volunteers, especially of the female. I decided that this was a pretty good 2 , so the next day I got ready to go. I arrived at Crossroads about five minutes 3 , and helped Alex and 4 of the volunteers. There were only three 5 at first, and we figured we might as well get started 6 just waiting for more to arrive. I held the 7 , and suddenly felt extremely shy. I did not 8 asking people for donations. In fact, I'm usually one of those people who try to 9 those boring stands and ask you for a little contribution. For heaven's sake, I can contribute to a few, 10 I cannot alone 11 every single cause in the world! I really didn't like the idea of asking anyone for donations to our cause. 12 , I watched my friends speak to the strangers, and noticed that they were extra polite to everyone-no matter whether they 13 . I realized that 14 I wasn't pushy (强求的), it would be okay, and my conscience could be 15 . I pasted on a large smile, and started asking people passing by. My mouth tripped over words, and I continually said"um" while I thought of the correct terms. 16 I talked to more and more people. Not only improved, but also started noticing small 17 . Instead of saying "donate", which made most people walk away 18 . I started suing the word "contribute". I added the phrase "every little bit counts", and people started to donate small amounts in larger quantities. As the day went on, I learned how to pull on the hearts of the 19 , and I became a successful fundraiser. At the end of the day, we all gathered at Alex's house and 20 how much money we raised. I was so surprised: we raised over $300! We celebrated, and went home tired, but satisfied that we helped a great cause. | ||||
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