配煤时适当配入瘦煤可提高（）。
A.化产品数量
B.焦炭的强度
C.焦炭的块度
参考答案：C
Technically, an individual is unemployed when he or she is actively seeking employment or is:（）
A. a retiree.
B. a discourage worker.
C. waiting to return to a job from which he or she was just laid off.
测定粗集料（碎石、砾石、矿渣等）的颗粒组成、干筛法筛分结果的计算若损耗率大于（），应重新进行试验。
A.0.10%
B.0.20%
C.0.30%
D.0.40%
