The aetiology of AD remains unknown and as yet, there is no known cure.

由于AD发病机理十分复杂，迄今为止尚不清楚，因此尚无理想的防治药物问世。

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The AD image above shows a pre-production sample which hadn't yet written "CD" next to the operation switch; the images to the right show it as finally produced.

上面的广告图片显示了一个预生产样品尚未写入“CD”的旁边操作开关，在右边的显示它的最后生产工序的图像。

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Ad rates are lower and, as yet, there is no ad format that seems perfectly primed to garner audience attention.

FORBES: Facebook Extends Charging For Messages. Great Move!

These initial results will, naturally, make investors more skeptical than they already are, yet as mentioned, the odds of success are presumably higher in non-carrier AD patients.

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Better yet, BrassRing could help these newspaper stalwarts capture help-wanted ad dollars as they slipped from print to the Internet.

FORBES: Help Wanted. Please!