题干

如图所示,我国自主研制的首艘货运飞船天舟一号,由长征七号运载火箭发射升空,地面控制中心通过____波向它发出指令,这种波在真空中传播速度为____ m/s.天舟一号在随火箭加速上升过程中,动能____(选填“变大”、“变小”或“不变”,下同),机械能____

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电磁,3×108,变大,变大

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Dear Mike,

      I'm so glad you're coming to China! Your mother,our foreign English teacher,told me you're worried about what you should and shouldn't do as a guest in China.Here's some advice.You will probably be invited to a big meal. You may find it earlier than you expect because Chinese people eat dinner much earlier than people in the West.There will be a lot of different dishes,not just three courses.You may find it difficult to use chopsticks if you haven't tried before.It's a good idea to get some practice.When the food is served,you should take time to look at it. The preparation takes a long time and everything will look beautiful.The plates will be placed in the middle of the table,for everyone to share.Take a little of everything and then have some more of the things you like.Chinese people like to talk about food,so it's a good topic of conversation.At the end of the meal,you will usually be served with fruit.Eat your fruit,thank your friends, and go.

      I hope this is helpful.E-mail me if you have any other questions. 

                                                                                                                              Yours,

                                                                                                                                   David Zhang