嗜铬细胞瘤致继发性高血压拟手术治疗，术前降压药用___________和___________联合治疗。
参考答案：α受体阻滞剂、 β受体阻滞剂治疗
论述农业推广工作的任务。
一 Yao Ming had to give up the rest of the season because of his broken leg.
一 _____[ ]
A. He was so careless.
B. Never mind.
C. That's all right.
D. What a pity!
