良性骨肿瘤的X线表现为( )
A．边缘清楚 B．出现葱皮现象 C．骨膜反应明显D．空腔形成 E．多处呈虫蛀状破坏
参考答案：A
School is over. We must go ________ now. [ ]
A. to class
B. home
C. to bed
D. to classroom
排土场的位置选择又怎么样的原则？
