假设一卡诺机工作于500℃和300℃的两热源之间，则卡诺循环的热效率为（）％。
参考答案：60.8
关井信号规定：长鸣笛时间为（）秒，短鸣笛时间为2秒。
A.5～10
B.10～15
C.20～25
D.25～30
A person who does not cheat on her income tax because she might get caught and sent to jail is demonstrating Kohlberg’s () stage of morality.
A．Postconventional
B．Preconventional
C．Formal operational
D．Conventional
