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？ | 
