Basically its any metal such as copper and aluminum you can also check your [[https://de.bab.la/woerterbuch/englisch-deutsch/Periodic%20Table|Periodic Table]] of elements and  THPT, [[https://lambangcapgiarenhat.com/lam-bang-thpt-tai-binh-duong-3/|lambangcapgiarenhat.com published a blog post]], try looking at some metals or metaloids