【多选题】下列关于农田土壤采样说法正确的是

【判断题】算术均数一定大于中位数。

【单选题】根据《粉尘作业场所危害程度分级》（GB／T5817-2009），作业场所粉尘时间加权平均浓度超过粉尘职业卫生标准3倍的，其危害程度应划分为（）级。

【单选题】Social Networking A large but long-in-the-tooth technology company hoping to become a bigger force in online advertising buys a small start-up in a sector that everybody agrees is the next big thing. ...

【单选题】A. As is known, we set great store by the trade relationship with the third world countries.B. We’ve never had any difficulties with our Chinese partners, and we ’ d like to make as many new contacts ...

【单选题】对于 X*=3 算术,与他等价的是( )。

【简答题】根据采样定理,采样频率应该

【单选题】执行二进制算术加运算盘+00100111其运算结果是( )。

【单选题】某地大气环境监测PM10的日平均浓度为0.45mg/m3，环境空气质量标准中PM10二级标准日平均浓度为0.15mg/m3，则超标倍数为______。

【单选题】要测得污染物日平均浓度每天至少采样几次（ ）。