- 下工夫 xiàgōngfu to put in time and energyTo spend a significant amount of time and effort in order to accomplish something or master a skill; also written as [[下功夫|下功夫|xia4 gong1 fu5]].
- 地下工作 dìxiàgōngzuò underground worksecret or clandestine activities, usually involving political or military groups
- 地下工厂 dìxiàgōngchǎng underground factoryan unlicensed or secret factory operating without official approval or legal registration