如图所示,动车快速行驶时,其上方气流的速度 (选填“大于,“小于”或“等于”)下方气流的速度,从而产生向上的升力;车厢内座椅下方的插座方便了旅客充电的需求,插座间的连接方式是 联;动车采用了“再生电制动”技术,即在制动时,列车由于惯性仍会向前运动一段距离,带动发电机发电,将 能转化为电能
(1)动车形状上凸下平,动车组行驶时机车上方空气的速度大于下方的空气速度,则上方的压强小于下方的压强,从而产生了向上的升力。
(2)插座是连接用电器的,车厢内的各用电器是并联的,故插座也是并联的。
(3)列车行驶带动发电机发电,将机械能转化为电能。
故答案为:大于;并;机械。
Dogs are the best pets of humans. They come in all sizes. Some dogs are as small as a football, and others are as tall as a desk. Dogs’ fur (毛) is different, too. It can be long and soft, or smooth and hard. People don’t mind the kind of fur, because all dogs are good to hug.
请在字典中查一下这个词。
我喜欢甜食, 你知道的。
去年, 彼得在旅途中和许多人交了朋友。
我叫托尼· 史密斯, 史密斯是我的姓。
我们在课上回答问题时应该起立
Tea and coffee are two of the most popular drinks in the world. However, people usually like one more than the other. These drinks also have very different uses.
People in the office usually sit for most of the day when they work. But this is bad for a person’s health. When people sit for too long every day, they don’t move very much. So it is easy to start getting fat. Sitting too long is also bad for their work because it makes them want to sleep. When this happens, people may make more mistakes in their work or spend more time finishing their work. Companies need workers to be healthy, so how do they fix the problem?