沉重地打击了匈奴，使其无力再与西汉对抗的战役是[ ]
A．长平之战
B．牧野之战
C．漠北战役
D．白登山之战
答案：C
热力膨胀阀的开度取决于（）。
A．蒸发器进口制冷剂压力
B．蒸发器出口制冷剂压力
C．温包压力
D．蒸发器出口过热度
According to Skinner, a well-known behaviorist psychologist, ______, was much more effective than ______ in a teaching situation.
A. reward...reasoning B. reward...punishmentC. reasoning...reward D. reasoning...punishment
