下列选项中,属于螺旋输送器的组成的是()。
A、电机
B、筒体
C、活塞
D、螺带
参考答案:A, B, D
填写下列表格中物质的化学式或名称,并填写物质所属类别(类别指单质、化合物、氧化物)
Food, gas and vegetables have been ________ by rail directly to the city ever since the highways
were blocked. [ ]
A. preferred
B. transported
C. packed
D. rescued