二甲苯的国家卫生标准是
A.40mg/m3B.100mg/m3C.80mg/m3D.90mg/m3E.120mg/m3
参考答案:B
解析:二甲苯的国家卫生标准是100mg/m3。
If law and order as well as rules and regulations _____, neither the citizen nor his property is safe.[ ]
A. are not observed
B. is not observed
C. were not observed
D. was not observed
装载传感器的平台叫[ ]
A、遥感平台
B、传感平台
C、工作台
D、开发基地