进行线路起道作业时,看道者应俯身在标准股上,一般情况下距起道机的距离为()。
A.10~20m
B.20~30m
C.30~40m
D.40~50m
参考答案:B
In the morning, Li Ming and Jenny ___________ quiet.[ ]
A. am
B. is
C. are
D. be
慢性肾衰患者的输血指征为血红蛋白小于80g/L