During this period, African-American actors were mostly limited to playing servants or African natives.

VOA: special.2010.05.23

There was a period of time in which, although there were decent, chess-playing programs couldn't beat the best chess-playing humans.

尽管曾一度出现过,强劲的象棋程序,无法战胜顶级人类棋手的情形

耶鲁公开课 - 死亡课程节选

Let's say oftentimes orchestral musicians, they're sitting there and they're not playing so they have to be able to count for a long period of time.

时常,管弦乐团的乐手们坐在那里,却不需要演奏,因此他们不得不打很长一段时间的拍子

耶鲁公开课 - 聆听音乐课程节选