冠词用an，原因：actor为元音发音开头。不定冠词有两个，a和an。a用在辅音开头的单词前面；an用于以元音开头的单词前。如：a book,an apple。
actor双语例句
Did you always want to be an actor?
你以前一直想当演员吗？
'No comment,' was the actor's stock response.
“无可奉告。”那位演员回答什么问题都是这一句老话。
A career as an actor requires one hundred per cent commitment.
干演员这一行需要百分之百的投入。
The smart money is on him for the best actor award.
内行认为他将获最佳演员奖。
He continued to pursue his goal of becoming an actor.
他继续追求他成为演员的目标。