It may be necessary to buy a new one.

也许有必要买个新的了。

《牛津词典》

No wonder he would rather repair the old bike than buy a new one.

难怪他宁愿修理旧自行车也不愿买新自行车。

youdao

Some small objects are so inexpensive that it's often easier to just buy a new one.

一些小物件非常便宜，直接买一件新的往往更容易。

youdao

The bride may buy a used gown rather than paying thousands of dollars for a new one.

VOA: special.2010.08.09

My aunt and I decided to buy a new electric refrigerator with the money I had sent her from California; it was to be the first one in the family.

我阿姨和我决定用我在加州给她寄的钱,买一个新的电冰箱;,家里的第一个电冰箱。

耶鲁公开课 - 1945年后的美国小说课程节选

For example, you want to buy a new car, because the old one has some problems But your wife throws cold water on the idea, because a computer costs too much.

VOA: special.2009.05.10

Every person I know who has Xbox, has had to buy a new one at LEAST once.

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And so, maybe you've got a 10-year-old car and you go out and buy a new one.

WHITEHOUSE: The White House

Then again, they'll probably just throw it out and buy a new one.

ENGADGET: 35lb, $6,500 1080p upscaler DVD player HD