疣状癌最常发生于
A．下唇
B．颊
C．舌背
D．牙槽黏膜
E．口底
参考答案：A
在地球同步轨道上的卫星绕行一周的时间大约需要36小时。
Which of the following changes would most likely decrease a firm’s demand for labor （）
A. Technological improvement in the firm’s production process.
B. Decrease in the price of the firm’s product.
C. Increase in the price of a productive input that is a substitute for labor.
