Because the normal allele (a) can completely cancel the mutant allele (a), animals with Aa or Aa look the same.

因为正常等位基因(A)可以完全取消突变等位基因(一)，动物使用AA或AA看起来是一样的。

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Purchase order shall mean a document or other request issued by AA Corporation if and when AA Corporation requests that Seller shall deliver the Equipment or a part thereof to AA Corporation.

订购单是指当AA公司请求卖方交付设备或部分设备时签发的文件或其他要求。

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Confidential information of AA company. Do not use, disclose or copy except with prior written consent from AA company. All whole or partial copies must bear this full legend.

AA公司保密资料。未经AA公司书面同意，不得使用、披露或复制。所有全部或部分复制件上都必须有此全部说明文字。

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As of last year, 97% of Cheyne's SIV debt portfolio was rated AA or higher.

FORBES

Currently, 80 percent of the bonds issued in China are backed by State credit and most of the rest come from large companies that have AAA or AA ratings.

FORBES: China In Transition

The AA's Mr King said "76% of AA members are cutting back on journeys, household expenditure or both, due to the high cost of fuel".

BBC: Budget 2013: Fuel duty rise cancelled by chancellor