有的误差主要是仪器本身造成的。
参考答案:对
—Mrs.Smith didn't come to the meeting, _____?
—No, _____.She was ill.[ ]
A. did he; he didn't
B. did he; he did
C. didn't she; she didn't
D. did she; she didn't
企业在自己的网页上发布采购物料的告示,吸引供应商上门,直接商谈采购事宜而进行的采购属于()。
A.非正规招标采购
B.正规招标采购
C.网上查询采购
D.定量订货法采购