HSK 6
工夫
gōngfu名
period of time (may be months, or mere seconds); spare time; skill; labor; effort
学好外语需要下不少工夫。
Xué hǎo wài yǔ xū yào xià bù shǎo gōng fu.
Mastering another language requires considerable effort.
Say it
Hold the button, say it, then let go.
Other HSK words sharing a character
Also free:
New in the HSK 3.0 word list at level 6.