According to paragraph 2 the "atmospheric engine" was slow becauseA．it had been designed
已帮助 人
According to paragraph 2, the "atmospheric engine" was slow because
A．it had been designed to be used in coal mines
B．the cylinder had to cool between each stroke
C．it made use of expanding steam to raise the piston in its cylinder
D．it could be operated only when a large supply of fuel was available
请帮忙给出正确答案和分析，谢谢！