【单选题】PLC 中专门用来接收外部用户输入信号的设备,称( )继电器。
【简答题】A.It costs less. B.It is flexible. C.It saves time. D.It grows fast.
【判断题】对流层和电离层有很强的相关性,通过求差可以把他们都消去。
【单选题】It saves time in the kitchen to have things you use a lot _______ easy reach.
【单选题】溺水者救上岸后,面色死灰,意识不清,口、鼻部有水草、淤泥,颈背部外伤出血明显,首先应立即采取的急救措施是:
【简答题】A.It poses a challenge to seniors。 B.It saves both time and money。 C.It is childish and unprofessional。 D.It is cool and convenient。