【单选题】When the trip coil of a circuit breaker is excited by a protective relay, the circuit breaker is ( ).
C.
connected to a fault element
【单选题】某患者,女,39岁,6个月前因外伤致一上前牙脱落,今要求烤瓷桥修复。口腔检查:右上中切牙缺失,间隙无明显异常,牙槽嵴高度无明显异常,较平整。左上中切牙近中切角缺损,未露髓,探稍敏感,叩诊阴性,无松动。右上侧切牙牙冠完好,叩诊阴性,无松动。上下前牙牙龈轻度红肿,易出血,可见少量菌斑及牙石,余牙未见明显异常。下列哪项关于右上侧切牙金瓷冠牙体预备的要求是正确的()
【单选题】a protective relay must operate at the ( )speed and must be reliable.
【简答题】第六次全国人口普查主要数据于2011年4月28日发布。读图2完成下列问题。 小题1:第六次人口普查登记的全国总人口数约为 A.14亿 B.13.4亿 C.12.8亿 D.12亿 小题2:从1990年到2010年,我国人口增幅是 A.快速上升 B.逐渐上升 C.逐渐下降 D.基本持平 小题3:我国把实行计划生育作为长期的一项基本国策,主要原因是 A.人口地区分布不均 B.农村人口比重大 C.城镇人口...
【单选题】The protective relay is a sensing device, which ( ) the fault, determines its location.
【简答题】It can be known that the writer of the 3rd greeting card lives home.
【判断题】PHP动态网站是用(PHP+数据库)开发的网站。
【简答题】With regard to humoral regulation, which
of the following is false ( )A. humoral regulation is not controlled by the
nervous system B. Through chemicals C. The cells that hormones act on are called...