清朝前期，闭关锁国政策严格地限制海外贸易。外国人来华贸易的唯一合法口岸是[ ]
A．广州
B．天津
C．北京
D．厦门
答案：A
Zhao Benshan, whose overwork _______ his health failure last year, is said to perform in the coming Spring Festival Gala on CCTV.
A．submitted to
B．admitted to
C．contributed to
D．subscribed to
高血压视网膜病变2级的眼底表现是（）
A.明显的小动脉狭窄及局部管径不规则
B.视网膜小动脉普遍变细，管径均匀，无限局性缩窄
C.视网膜出血、渗出和棉絮斑
D.视 * * 水肿和视网膜水肿
E.视网膜新生血管
