Colors are traditionally shown in a color wheel, and from this wheel, we can separate colors into three main groups: primary, secondary and tertiary.

色彩按照惯例被显示在色环中，从中我们可以将所有颜色分为三类：基色，次生色和三次色。

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According to the function, the wheat roots could be divided into 3 groups: primary root group, lower secondary root group and upper secondary root group.

依照各单位根的功能，小麦根可分为3组：初生根组、次生根下位组和次生根上位组。

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As IDAHO day is marked by activities in schools, the IDAHO Committee and UNESCO have co-developed a lesson plan which includes four classroom activities for different age groups (primary and secondary level) to address issues of discrimination and homophobic bullying.

UNESCO: WORLDWIDE

Earlier this week, the island's education department announced an end to nurture groups in both the primary and secondary sector.

BBC: Teachers call for 'reversal' of special needs decision