井下危险地点作业，严禁（）作业。
A.单人
B.多人
C.单工种
D.多工种
参考答案：A
We were asked to________a note of what he said and________notes afterwards. [ ]
A. take; make
B. keep; compare
C. make; compare
D. make; take
延迟裂纹一般认为潜伏期和（）扩展期与氢的聚集有关，所以又称氢致裂纹或延迟裂纹。
A、急剧
B、缓慢
C、匀速
D、变速
