柯林斯詞典optional /??p??n?l/ 1. ADJ If something is optional, you can choose whether or not you do it or have it. 可選擇的 Sex education is a sensitive area for some parents, and thus it should remain optional. 性教育對(duì)一些家長(zhǎng)來說是個(gè)敏感的話題，因此應(yīng)該還是非強(qiáng)制性的。 返回 optional劍橋詞典If something is optional, you can choose if you want to do it, pay it, buy it, etc. 可選擇的；非強(qiáng)制的 English is compulsory for all students , but art and music are optional. 英語是所有學(xué)生的必脩課，而藝術(shù)和音樂則是選脩的。 例句 Seat-belts are included as standard but electric windows are an optional extra .My phone came with 20 optional ringtones .Do come to the party - fancy dress is optional.There are several optional tours , for which there will be a small charge .The basic model is quite cheap , but there are a lot of optional extras . 返回 optional