非芳烃中含芳烃量大的原因是（）。
A、抽提溶剂比过小
B、反洗比过小
C、温度低
参考答案：A
What was one result of the increased use of machinery on farms of the United States
A．Prices for farm produce rose.
B．Farmers became more dependent on loans from banks.
C．Jefferson established government programs to assist farmers.
D．Farmers relied less on foreign markets.
斜坡矿车运输，随着倾角加大，颠覆力矩越大，矿车的稳定性越差。就稳定性而言，存在临界倾角，对于钢丝绳运输，这个倾角为（）。
A.25°
B.30°
C.32°
D.35°
