继电保护直流系统一点接地持续时间()以内,定为设备异常。
A、8小时
B、6小时
C、4小时
参考答案:A
—We've waited for the two singers for two hours. Will they be able to come here?
—I'm afraid ____ of them will come today. [ ]
A. neither
B. either
C. both
D. none
缺铁性贫血患者的典型红细胞形态是()
A.巨红细胞
B.大红细胞
C.球形红细胞
D.红细胞大小不均
E.低色素性小红细胞