如臂使指

如臂使指	rú bì shǐ zhǐ	as the arm moves the finger (idiom) / freely and effortlessly / to have perfect command of
如	rú	as / as if / such as
臂	bì	arm
使	shǐ	to make / to cause / to enable / to use / to employ / to send / to instruct sb to do sth / envoy / messenger
指	zhǐ	finger / to point at or to / to indicate or refer to / to depend on / to count on / (of hair) to stand on end