与动火监护人的职责不符的行为是（）
A.检查现场用火环境
B.检查用火时间、用火部位
C.可以离开现场做其他工作
D.落实措施
参考答案：C
We have been excavating layers of ash almost six metres thick, which suggests that they________the fire burning all winter.
A．should keep
B．might have kept
C．should have kept
D．might keep
维生素D缺乏性手足搐搦症的直接原因是（）
A.维生素D缺乏
B.血磷明显降低
C.碱性磷酸酶增高
D.血清离子钙降低
E.钙磷乘积降低
