水不宜用于扑灭电气设备的着火，如需用水救电气着火时一定要先（）。
参考答案：切断电源
The old man has expected to see all his children when he was in hospital, but ______ came to see him.
A．none
B．no one
C．someone
D．anyone
霍奇金病最常见的首发症状是()
A．颈部和锁骨上淋巴结肿大
B．持续性或周期性发热
C．肝、脾大
D．皮肤瘙痒
E．外周血白细胞增高
