History is an
optional subject at the college.
历史学是该校的一门选修课。
Eric doesn't like taking compulsory course but
optional course.
埃里克不喜欢上必修课，而喜欢上选修课。
I might go to the gym after work, but it's not certain.
我可能下班后去健身房，但不肯定。
The dress code for the party is
optional, so you don't have to wear a suit.
聚会的着装要求是可选的，所以你不必穿西装。
Attending the extra classes is
optional, but it can greatly improve your understanding.
参加额外的课程是自愿的，但它可以大大提高你的理解力。
You can choose to have breakfast in the hotel, or you can skip it if you prefer.
你可以在酒店吃早餐，或者如果你愿意，可以选择不吃。
The dessert is
optional, so feel free to have it or not.
甜点是可选的，所以你可以随意选择吃或不吃。
The survey includes an
optional section where you can provide additional feedback.
调查包括一个可选的部分，你可以在那里提供额外的反馈。
The swimming lesson is
optional, so only those who want to participate need to sign up.
游泳课是自愿的，所以只有想参加的人需要报名。
The final exam has an
optional essay component, which could boost your overall grade.
期末考试有一个可选的论文部分，这可能会提高你的总分。
The software update is
optional, but recommended for improved performance.
软件更新是可选的，但为了提高性能，建议进行更新。
The donation to the charity is entirely
optional, no one will pressure you.
对慈善机构的捐赠完全自愿，不会有人强迫你。
It is also optional for some companies with high-quality assets and great performances to be listed on stock markets independently, he said.
他说，对于一些拥有优质资产和良好业绩的公司来说，独立上市也是可选的。
"There are three principles that govern inspection of formulas－necessary nutrients must be added; optional nutrients need to be marked clearly; and dangerous ingredients, including additives, are banned," he said.
The income and price elasticity of optional consumption sectors, such as education, entertainment, transportation and medical care, is relatively high, and these sectors are exactly where sluggish consumption is witnessed.
Digital transformation, no longer optional, is now imperative as it emerges as a new growth engine.
We offer a curated selection of included and optional shore excursions that give guests a unique cultural experience at each destination," said Wee-Hoon Tan, senior vice-president of product development and marketing at China Merchants Viking Cruises.
It insists on an ID that India's Supreme Court had already ruled is inessential or optional.
In Germany, it has already introduced an optional Level 3 system into the S-Class and the all-electric EQS in compliance with local regulations.
For instance, China's electric vehicle brand AITO provides a 10,000 yuan optional package fund, and 5,000 yuan of the Beijing brand replacement discount.
The SUV offers aviation-grade seats with optional six- and seven-seat layouts.
The optional Bentley Diamond Illumination uses LEDs that emit light through small perforations that measure 1 mm in diameter in the leather trim on the door panels.