即席讲话 speak impromptu;make an impromptu speech;off-the-cuff remarks
极限运动 extreme sports;X-sports
集思广益 draw on collective wisdom and absorb all useful ideas
集中供暖 central heating
集资办学 raise money to set up new schools
集资房 houses built with funds collected by the buyers
计划经济 planned economy
计划内招生 planned enrollment
计时工资 hourly wage
计时工资制 time-rate wage system
纪念封 commemorative envelope
纪实文学 documentary writing
纪实小说 documentary fiction
技工学校 skilled workers training school