hỏi một thắc mắc 
to ask a question [ hỏi ] : (1) to ask, inquire, question; (2) low-rising tone
[ một ] : one; a, an
[ mắc ] : (1) to be expensive; (2) to be caught (in a trap, disaster), hang on a peg
Most Common Compounds Set 1:
Most Common Compounds Set 2 :