primary function

基本解释

And even if they are still called “phones”—a word derived from the Greek word for voice—making voice calls may no longer be their primary function.
即使它們仍被我們叫做“電話”（電話這個詞源自希臘語中的“聲音”一詞），打電話可能不再是它們的主要功能了。
A multitude of separations are accomplished by distillation, but its most important and primary function in the refinery is its use for the separation of crude oil into component fractions.
許多分離過程是通過蒸餾進行的，但蒸餾在鍊油廠中的最重要和主要的功能則是它在將原油分離成不同餾分過程中的作用。
The primary function of the human mind is its ability to absorb information and adapt to challenging unfamiliar environments.
人類大腦的主要功能就是吸收信息的能力和挑戰陌生環境的適應性。

He says a primary function of the home is to give migrants a safe place to sleep and something to eat as well as to provide them with information about the dangerous journey ahead.

As for that detachable scope, it's primary function is window dressing.
ENGADGET: blogger-avatar
In most developed markets, the primary function of an equity market is to provide price discovery, allowing successful companies to raise capital for profitable investment opportunities.
FORBES: Chinese Stock Market -- Buy In or Buyer Beware?