a tree一棵树aart.一(个)；每一(个)；任一(个)n.英语字母表的第一个字母；学业成绩得优者；表示“最好”的符号a one-hour lunch break一小时午餐时间a closely guarded secret严守的秘密A magnet attacts iron.磁石吸引铁。A member of a kibbutz.基布兹成员a life full of adventure充满惊险刺激的生活A specialist in Latin.拉丁语学者a stringent money market银根紧的货币市场a disarmament conference裁军会议a pop-up birthday card立体生日卡a treatise on mineralogy矿物学论文

1. Here is a congenital bicuspid aortic valve.
   这是一个先天性的两瓣叶主动脉瓣。
2. This angiogram demonstrates the aortic arch and great vessels.
   血管造影显示主动脉弓和大动脉。