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

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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!