100句话7000单词-Day19

Day19. When it is struck, a tuning fork produces an almost pure tone, retaining its pitch over a long period of time. 
 当音叉被敲击时，会产生几乎纯质的音调，且经久不衰。 Tune 美 [tu:n] n. 曲， 调， 心情， 和谐；v. 调整（音频／音调），使和谐一致 You've changed your tune since this morning, haven't you? 你从今天早上就变卦了，是不是？ It was just an ordinary voice, but he sang in tune. 他嗓音很一般，但唱得都在调儿上。 Retain 美 [rɪˈten] v. 保持，留在心中，雇佣 Mark retains a deep respect for the profession. 马克对这个职业仍然深怀敬意。 He decided to retain Louis for the trial. 他决定聘请路易为出庭律师。 Pitch 美 [pɪtʃ] n. 音高，最高点；v. 投抛， Simon pitched the empty bottle into the lake. 西蒙把空瓶子扔到湖里。 His voice was pitched high, the words muffled by his crying 他的声调很高，嘴里的话因哭泣而含混不清。