optional
adj
that may be chosen or not, as one wishes; not compulsory 可选择的; 随意的; 非强迫的
optional subjects at school 学校的选修课
Formal dress is optional. 是否穿礼服自便.
The cassette player is an optional extra in this make of car, ie It will cost extra if one chooses to have it. 这种型号汽车如需盒式磁带唱机费用另计.
Let me think. Maybe I could ask Jeanne. She married a man with a lot of money. I'll go and see her on Friday after I get the new dress.
我想想看。或许我可以去问问让娜。她嫁给了一位很有钱的男人。等我买好新衣服,星期五就去看她。
My dear friend, Mathilde. Let me tell you something. That necklace you borrowed from me wasn't a real diamond necklace. It wasn't valuable at all. The stones in the necklace were made of glass. It was worth five hundred francs at the most.