分类： IGCSE

阅读材料 8.1 Arrangement of ele…

The elements between Group II […]

All of the noble gases are pre […]

1. Halogens The halogen family […]

1. Alkali metals Group I eleme […]

1. The structure of periodic t […]

阅读材料 10.1 Water 10.2 Fertil…

Plants make their own food by […]

1. Components of air The compo […]