【简答题】热机是把______能转化成______能的机器,______是最常见的热机.
【单选题】Which of the following statements about labor unions can be concluded based on the information in the passage?
A.
Labor unions reached their peak of power in the 1986's.
B.
It took labor unions many years to improve conditions for workers.
C.
The early labor unions failed .because they were not concerned with the well-being of workers.
D.
The early labor unions failed because they could not agree on what they wanted to fight for.
【简答题】热机的分类:最早的热机是______;其次是______;______;______.
【单选题】下列关于热机的效率,说法正确的是 [ ]
【简答题】热机是将内能转化成______能的机器;如图所示是热机的______冲程.
【单选题】甲、乙两台热机,甲的效率比乙的低,其含义是( )
【简答题】______是最早的热机.现代热机种类繁多,构造各异,有______、______、______、______.
【单选题】关于热机的效率,下列说法中正确的是( )
【简答题】热机是将内能转化成____________能的机器。下图所示是热机的____________冲程.