All-key,关系模型的所有属性组是这个关系模式的候选码称为全码 若关系中只有一个候选码,且这个候选码中包含全部属性,则该候选码为全码
连接你的iPhone,然后在iPhone里输入显示在Mac电脑上的安全码。
Connect to your iPhone, and enter the security code that appears on your Mac into your iPhone.
大部分信用卡和借记卡需要背面的安全码进行在线支付。
The security code on the back of most credit and debit CARDS is required to make payments online.
但是我们不会以此方式保存与您支付工具有关的安全码。
We do not, however, retain the security code associated with your Payment instrument in this manner.
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