By installing special electric pumps, farmers' houses could be heated by the warmth from cows's milk,accoring to one agricultural engineer.

A  farmers' houses could be heated by the warmth from cows's milk,accoring to one agricultural engineer.

B  the warmth from cows's milk could be used by farmers to heat their houses, according to one agricultural engineer

C  one agricultural engineer reports that farmers could use the warmth from cows's milk to heat their houses

D  farmers, according to one agricultural engineer, could use the warmth from cows' milk to heat their houses

E  one agricultural engineer reports that farmers' houses could be heated by the warmth from cows' milk

答案为A，我选的是C， installing sepcial electric pumps 主语不是应当是agricultural engineer 吗？

这个题，我也迷糊了，我开始选D，请教：

介词之后的动名词的结构是否不需要，逻辑主语一致。

 对，我突然想起来：只有 当 By结构引导 的是 被动结构的时候， By之后的动

名词（是实际上的主语），不需要考虑主谓一致，其余情况，做adverbial phrase的

时候，都要主语一致。