通常，下列哪几种情况油罐进油流速不得大于1m/s。（）
A、空罐进油
B、进油口至起伏线
C、接近起伏线至浮起
D、浮起后
参考答案：D
双端固定桥固位不良的原因有
A．固位体设计不当，固位力不足
B．两端的基牙数目不等
C．基牙制备时，轴面聚合度过小
D．桥体强度不足
E．一端固位体的固位力略高于另一端
---Cliff, I lost your bike at school. I suppose I should pay for it.
---Oh, ______. It was an old bike anyway.
A．take it easy
B．OK
C．don’t say so
D．forget it
