一般采用()近似公式来估算清管所需总时间。
A.t=L/F
B.t=L/P
C.t=L/Q
D.t=L/V
参考答案:D
Is _____ three hours _____ the boy _____ family is poor to come to school on foot?[ ]
A. it; that; whose
B. it; that it takes; whose
C. it for; that it takes; whose
D. it; when; that
我国安全生产的工作方针是()。
A.安全第一、预防为主、综合治理
B.安全第一、预防为主
C.以人为本、安全发展