One factor contributing to the two-party system in the United States is the single-member district system of electing Representatives.

导致美国两党制的一个原因是，每个国会议员选区只能选出一名代表。

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Hence, such a system will mitigate the risk associated with the use of single-security mechanisms in both the factors in a two-factor authentication.

因此，这种系统降低了使用单一安全机制实现两因素身份验证的风险。

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A two-factor authentication system has been replaced by a three-factor system which is more secure but less convenient.

双重认证变成了三重认证，虽然提高了安全性，但却更不方便了。

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The "two-factor" verification system, which will be optional, asks users to register a phone number, e-mail account and six-digit code that would have to be entered, via text message, each time they log in to the site.

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