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, and 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")