轮对的作用是承载电机车的（），传递机车的正压力、牵引力和制动力 A.全部负荷 B.全 发布时间：2018-01-23 04:16 │ 来源：www.tikuol.com 题型：单项选择题 问题： 轮对的作用是承载电机车的（），传递机车的正压力、牵引力和制动力A.全部负荷B.全部牵引力C.全部质量D.全部重量
题型：单项选择题 煤或焦炭中的灰熔点取决于灰分中的酸性氧化物和碱性氧化物含量及其比例，如果灰分多而且灰熔点低，气化时料层中易结渣。因此，一般要求气化原料的灰分熔点大于或等于1000℃较为适宜。 查看答案
题型：单项选择题 The sun today is a yellow dwarf star. It is fueled by thermonuclear reactions near its center that convert hydrogen to helium. The sun has existed in its present state for about 4 billion, 600 million years and is thousands of times larger than the Earth. By studying other stars, astronomers can predict what the rest of the sun’s life will be like. About 5 billion years from now, the core of the sun will shrink and become hotter. The surface temperature will fail. The higher temperature of the center will increase the rate of thermonuclear reactions. The outer regions of the sun will expand approximately 35 million miles, about the distance to mercury, which is the closest planet to the sun. The sun will then be a red giant star. Temperatures on the earth will become too hot for life to exist. Once the sun has used up its thermonuclear energy as a red giant, it will begin to shrink. After it shrinks to the size of the earth, it will become a white dwarf star. The sun may throw off huge amounts of gases in violent eruptions called nova explosions as it changes from a red giant to a white dwarf. After billions of years as a white dwarf, the Sun will have used up all its fuel and will have lost its heat. Such a star is called a black dwarf. After the Sun has become a black dwarf, the earth will be dark and cold. If any atmosphere remains there, it will have frozen onto the earth’s surface.The word "fueled" underlined in Paragraph 1 most probably means ______ .A．poweredB．bombardedC．createdD．pushed 查看答案