登革热的传播媒介是() ["蚊","人虱","鼠蚤","恙螨","蜱"]
关于电泳分离中迁移率描述正确的是() ["带电分子所带净电荷成正比","分子的大小成正比","缓冲液的黏度成正比","以上都不对"]
()是用以反映工作机械的行程位置,发出命令以控制运动方向或行程大小的一种电器,它的作用与按钮相同,也是用来接通和断开控制电路。 ["接触器","低压断路器","行程开关","组合开关"]
神经衰弱的记忆力减退是由于() ["睡眠障碍","思维迟钝","情绪不稳","注意力难以集中","焦虑不安"]
世界三大饮料是指()。 ["矿泉水","啤酒","茶","咖啡","可可","白兰地","可乐"]
圆筒混合机的工艺主要指哪些?