这位年轻士兵为了执行任务特意保持面部清爽。

The young soldier kept himself ___smooth-faced for the mission.

这位40岁的演员看起来依然面容光滑，像个小伙子。

The 40-year-old actor still looks ___smooth-faced, like a young man.

那个表面和善的政客总是承诺一些他永远不会兑现的事情。

The ___smooth-faced politician always promises things he will never deliver.