Some characters containing 青
On its own, 青 qīng means 'blue' or 'green'.
清 is still qīng but means 'pure'.
请 has a different tone: qǐng
It basically means 'request' or 'invite', but also functions as 'please' in some situations.
These characters are used in the following words:
青年 qīngnián 'a youth'
清楚 qīngchu 'clear' (adjective and resultative complement)
请问 Qǐng wèn 'Excuse me' (common way of asking a question "please let me ask you")