【单选题】She said her brother ____ in Beijing. He ______ to Japan on business last week.
【单选题】直流稳压电源中,滤波电路的作用是( )
D.
使输出直流电压不随电网电压或负载的变化而变化
【判断题】设计一对渐开线直齿圆柱齿轮时,若实际中心距不等于标准中心距,采用变位齿轮可以实现无侧隙啮合。
【判断题】设计一对渐开线直齿圆柱齿轮时,若实际中心距不等于标准中心距,采用变位齿轮可以实现无侧隙啮合。
【单选题】She said her brother ____ in Beijing. He ______ to Japan on business last week.
【单选题】She said her brother ____ in Beijing. He ______ to Japan on business last week.