八位老师带59名同学去公园划船,每只船限坐9人,他们至少要租几只船?
59+8=67(人),
67÷9=7(只)…4(人),
7+1=8(只);
答:他们至少要租8只船.
They will_________the old houses to build the central park. [ ]
A. put off
B. pull down
C. put down
D. put up
一同学用50牛的力沿水平面推一重100牛的箱子前进了20米,他对箱子做的功是多少?