吊装曳引机时应使机座处于()位置,平稳起吊,抬扛重物应注意用力方向及用力的一致性,防止滑杠脱手伤人。
A、垂直;
B、水平;
C、倾斜一定角度;
参考答案:B
—Why does the lake smell terrible?
—Because large quantities of water_________. [ ]
A. have polluted
B. is being polluted
C. has been polluted
D. have been polluted
教案对于()相当于()对于分类
A.课件;信息
B.教学;归类
C.提纲;商品
D.授课;标准