You use extra to describe an amount, person, or thing that is added to others of the same kind, or that can be added to others of the same kind.
Police warned motorists to allow extra time to get to work.
警察告诫驾车者留出富余的时间去上班。
There's an extra blanket in the bottom drawer of the cupboard.
衣橱的底柜有一条备用毯。
If something is extra, you have to pay more money for it in addition to what you are already paying for something.
For foreign orders postage is extra.
对于国外订单,邮资是另计的。
If you are charged extra for something, you have to pay more money for it in addition to what you are already paying.
You may be charged 10 extra for this service.
你可能会因该项服务而被额外收取10的费用。
You can use extra in front of adjectives and adverbs to emphasize the quality that they are describing.
I said you'd have to be extra careful.
我说过你必须格外小心。
extras
Extras are additional amounts of money that are added to the price that you have to pay for something.
There are no hidden extras.
没有任何隐性的额外费用。
Extras are things that are not necessary in a situation, activity, or object, but that make it more comfortable, useful, or enjoyable.
Optional extras include cooking classes at a top restaurant.
可选的额外选项包括一家高级餐馆的烹饪课程。
The extras in a film are the people who play unimportant parts, for example, as members of a crowd.
In 1944, Kendall entered films as an extra.
1944年,肯德尔作为一名临时演员进入电影界。
You use extra to refer to the amount of money you have to pay for something in addition to what you are already paying for it.
She won't pay any extra.
她不会支付任何额外费用。