【多选题】下列( )是 步进电机的特点 ?
C.
控制简单,开环,无须参数设计及调整,不存在稳定性问题;
D.
速度取于脉冲信号的频率,位移量取决于脉冲数。
【判断题】滞纳金或者提供纳税担保的,税务机关可以阻止其出境。( )
【判断题】若线性规划的原问题有无穷多个最优解时,其对偶问题也一定有无穷多个最优解。
【单选题】196 The project manager must receive reports and briefings from engineers, contracting officers, procurement personnel and marketing people. The project manager's communication dilemma is one of:
【判断题】若线性规划的原问题有无穷多个最优解时,其对偶问题也有无穷多个最优解。( )
【单选题】114 The project manager must receive reports and briefings from engineers, contracting officers, procurement personnel and marketing people. The project manager's communication dilemma is one of:
【单选题】室内空气污染的主要来源之一,是室内装饰材料、家具、化纤地毯等不同程度地释放出的有毒气体,其主要成分是()