前面加an，因为它是元音开头的:
/ˌɒpəˈreɪʃn/
n. 操作经营[外科] 手术[数][计] 运算
The operation saved her life.
手术挽救了她的生命。
Will the operation leave a scar?
手术会不会留下疤痕
Will I need to have an operation ?
我需要动手术吗
There are three ski lifts in operation.
有3辆滑雪缆车在运行。
He's mending slowly after the operation.
手术后，他正在缓慢好转。
