患者，男，65岁。因反复右下肢疼痛1个月余来诊，诉疼痛自右臀部沿大腿后侧下行放射至小腿后外侧，行走疼痛加重，夜间著，无麻木感。患者2个月前曾查体发现肝癌行手术治疗。查体腰椎无明显压痛，双侧直腿抬高试验阴性，右臀部坐骨神经出口处压痛。门诊行坐骨神经阻滞后，疼痛立刻缓解，2天后疼痛渐出现，1周后复诊诉仍有疼痛，但较前有所减轻，要求进一步处理。

放射治疗是骨肿瘤重要治疗手段之一，对癌痛具有很好的缓解作用，其作用机制主要包括（）

A.破坏癌性组织，使肿瘤缩小或消失，从而解除局部压迫及堵塞

B.抑制正常骨细胞释放化学性致痛介质

C.促进正常骨细胞释放化学性镇痛介质参与止痛过程

D.直接破坏外周末梢神经组织，阻断疼痛的中枢传入

E.破坏肿瘤周围血管组织，使肿瘤组织缺血坏死，体积缩小，解除对神经的压迫

F.促使中枢神经系统释放内源性镇痛物质如阿片肽等参与镇痛过程

Quality and grade are not the same. A fundamental distinction is that ______ .

A．grade is a category assigned to products or services having the same functional us but different technical characteristics

B．low quality may not be a problem; low grade is always a problem

C．determining and delivering the required levels of quality are not included in the responsibilities of the project manager and the project team

D．determining and delivering the required levels of grade are not included in the responsibilities of die project manager and the project team