高血压病患者，伴变异型心绞痛，最佳降压药物为（）
A.钙拮抗药
B.利尿药
C.β受体阻滞药
D.α受体阻滞药
E.ACEI
参考答案：A
She offered me practical _____ with my research, for which I would appreciate for my whole life.[ ]
A. conduct
B. certificate
C. admiration
D. assistance
等比数列{an}的前n项和为3n-1，则数列{an2}的前n项和为______．
