Class, please stand ______. [ ]
A. down
B. up
C. to
D. in
答案:B
计算:
1-3+5-7+9-11+…-1999+2001=______.
机动翻斗车下坡及转弯时,严禁空档滑行。往基坑内卸料,接近坑边时应减速,坑边应设置挡木,且挡木与坑边保持不小于()的安全距离。
A.1m
B.2m
C.3m
D.4m