天津家教:高考必背语句十九

来源：天津津师吧家教中心日期：2013-4-16

The mechanism by which brain cells store memories is not clearly understood. 大脑细胞储存记忆的机理并不为人明白。

When it is struck, a tuning fork produces an almost pure tone, retaining its pitch over a long period of time. 音叉被敲击时，产生几乎纯质的音调，其音量经久不衰。