A distinction should be made between the primary and secondary tasks.

要区别主要的和次要的任务。

《新英汉大辞典》

youdao

Can we just backtrack a little bit and look at your primary and secondary education?

我们能否稍微回顾一下刚刚提及的你的中小学教育背景？

《柯林斯英汉双解大词典》

Right, but if you just got the primary exposure, wouldn't the secondary response automatically-- not a booster shot, just the secondary response, because you were exposed?

但这时你已经获得这样的初次免疫,而因为你已经天然感染过该病毒,那么,在没有加强针的情况下,二次免疫是否无法自动发生

耶鲁公开课 - 生物医学工程探索课程节选

The government has set ambitious targets with few resources to ensure that the country's more than 10m primary- and secondary-school teachers acquire the skills and determination to change the habits of a lifetime.

ECONOMIST: China

This eventually translated into a series of government programs, such as state-funded primary and secondary schooling, the adoption of a five-day, forty-hour workweek, elimination of child labor, introduction of welfare and unemployment services, senior income support, workplace safety regulations, environmental regulations, and eventually some form of universal healthcare.

FORBES: Let's 'Clean Sheet' Our Failed Approach To Entitlements

Enrolment in pre-primary, secondary and tertiary education has also grown by more than 60% during the same period.

UNESCO: EDUCATION