For many years the motive power of train be steam这里面为什么用be

题目

For many years the motive power of train be steam这里面为什么用be
用其他动词可以吗,请详细讲讲

答案

这句话错误,不该是be,而应该是was,be是be动词原形.不能直接使用作谓语
因为蒸汽做火车动力是过去的事情.所以使用一般过去时
For many years the motive power of train was steam.好多年,火车的动力是蒸汽.