钻研

钻研	zuān yán	to study meticulously / to delve into
钻	zuàn	variant of 钻
钻	zuān	to drill / to bore / to get into / to make one's way into / to enter (a hole) / to thread one's way through / to study intensively / to dig into / to curry favor for personal gain
钻	zuàn	drill; auger / diamond
研	yán	to grind / study / research