(can make oneself)usefulin some kind of work; capable of one specific job;expert in some kind of work; have the expertise in one speciality; proficiency in a particular field;skilful (/well-versed) in one line ? 這些人員中，凡有～而無嚴(yán)重的反動(dòng)行為或嚴(yán)重的劣跡者，人民政府準(zhǔn)予分別錄用。(《毛澤東選集》1347) The People’s Government will permit the employment of those among them who can make themselves useful in some kind of work and have not committed any grave reactionary act or other flagrant misdeed./……獎(jiǎng)勵(lì)他們的～，一滴之功。(《中國(guó)農(nóng)村的社會(huì)主義高潮》300) …and their every skill and merit were awarded.
一技之長(zhǎng)
proficiency in a particular line or field;professional skill;master of sth
一技之長(zhǎng)yī jì zhī chánɡ
技：技能、本領(lǐng)；長(zhǎng)：專長(zhǎng)。指有某種特長(zhǎng)。specialty, skilful in one field, well versed in one line, a single skill