When writing element symbols, we should pay attention to the following points: ① the element symbols represented by a letter should be capitalized; An element symbol represented by two letters, the first letter is capitalized and the second letter is lowercase.
The elemental symbols of sulfur are: s; The elemental symbol of mercury is: Hg; The symbol of potassium is: k;
O is the symbol of oxygen; Mn is a symbol of manganese.
So the answer is: s; Hg； k； Oxygen element; Manganese element.