对硅稳压管电源进行调试时，应保证在交流电源电压波动（）时，直流稳压输出电压稳定不变。
A、5％
B、10％
C、15％
D、20％
参考答案：B
His father, a famous university professor, who is said to have started his teaching career in Australia, _____ in Nanjing University for more than twenty years.
A．has worked
B．worked
C．is working
D．will work
IgA肾病的预后与下列哪些因素无关（）
A.起病年龄越大，相对预后越差
B.有肉眼血尿者易发生肾衰竭和高血压
C.尿蛋白>1g／d者，预后较差
D.伴高血压者预后差
E.IgA沉积量多者预后差
