送交者: steven 于 2010-12-19, 23:06:16:

回答: on a complex plan. 由 steven 于 2010-12-19, 23:02:04:

• you know music, but not sound. (无内容) - OO8 (0 bytes) 2010-12-20, 01:51:08 (527850)
  • you think the sound wave propagates through air - steven (28 bytes) 2010-12-20, 02:05:07 (527857)

加跟贴