机械密封与填料密封相比()的功率消耗较大。A、机械密封 B、填料密封 C、差不多 发布时间:2017-07-29 02:41 │ 来源:www.tikuol.com 题型:单项选择题 问题: 机械密封与填料密封相比()的功率消耗较大。A、机械密封B、填料密封C、差不多
题型:单项选择题 500kV变电站站用电源接法最不合理的是()。A.由主变压器第三绕组引接;B.有较低电压母线时,从这类母线上引接两个站用电源;C.无较低电压母线时,直接从高压母线上引一台站用变压器;D.由附近的发电厂或变电站低压母线引接 查看答案
题型:单项选择题 important, friend, mean, them, stand, itself, child, remember, age, weather, pleasant, feel Have you heard of small talk? It 小题1:________ that the conversation is about some little things, which are not 小题2:________. You can make small talk when 小题3:_________ in line in the supermarket or while waiting for the bus. Though the topics in small talk aren’t important, small talk 小题4:________ is very important. It makes people 小题5:_________relaxed; It breaks the silence; It shows 小题6:________ and good manners; And it makes time pass 小题7:________.In small talk, it’s important 小题8:________ to smile and keep the conversation relaxed. It’s also good to show a sense of humor. You could talk about the 小题9:_________ , an interesting story on TV, a sports event, a play or a movie, and you could ask parents about their 小题10:_________. 查看答案
题型:单项选择题 电子质量为m,电荷量为e,从坐标原点O处沿xOy平面射入第一象限,射入时速度方向不同,速度大小均为v0,如图所示。现在某一区域加一方向向外且垂直于xOy平面的匀强磁场,磁感应强度为B,若这些电子穿过磁场后都能垂直射到荧光屏MN上,荧光屏与y轴平行,求: (1)荧光屏上光斑的长度; (2)所加磁场范围的最小面积。 查看答案