从事尾矿库放矿、筑坝、排洪和排渗设施操作的专职作业人员被招聘后，必须经过尾矿库企业对其培训，方能上岗作业。
参考答案：错
It was _____ the man came up and spoke to me _____ I realized he was all old friend of mine. [ ]
A. when; then
B. while; which
C. not until; when
D. when; that
带表卡尺在测量时，只要将量爪与产品接触就行，推力的大小无关紧要。
