这些2009年五月引进Bing所作的准备，将迎来六个月周期性的升级。
The upgrades have come in six-month cycles since the preparations for Bing’s introduction in May 2009.
在12月份下旬，一直受周期性欧洲经济危机影响而波动的美元重回低位。
In late December, the dollar resumed a decline that has been interrupted only by periodic European crises.
从12月份开始就一直在那里，慢慢的在St Croix和St Thomas之间交叉往来65公里，周期性的浮出水面再潜回4000米的深处。
It has been there since December, slowly criss-crossing the 65km between St Croix and St Thomas, periodically surfacing and then diving back down again to depths of 4, 000 metres.
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