男性,52岁。在行走中突然摔倒,呼之不应,呼吸停止,颈动脉搏动消失。最可能的原因是()
A.脑出血
B.癫痫发作
C.心脏骤停
D.高血压脑病
E.脑血栓形成
参考答案:C
It has been proved______eating vegetables in childhood helps to protect you against serious illnesses in later life.
A.if
B.because
C.when
D.that
一台给低压照明电路供电的变压器,初级所加交流电压为u="311sin314t" V。能够使次级获得有效值为36V的安全电压,它的初、次级线圈匝数之比应为__________。当次级电路使五盏“36V 40W”的灯泡正常发光时,它的初级电流的有效值是___________A。(该变压器可视为理想变压器)