không biết làm gì 
to not know what to do [ không ] : (1) no, not; (question tag); (2) air; (3) empty
[ biết ] : to know, know how to do (something) be aware of
[ làm ] : to do, work, make, function as, serve; to cause something to happen
[ gì ] : what
Most Common Compounds Set 1:
Most Common Compounds Set 2 :