It isn't installed by default, but is available as one of the optional program files, so you must select it during installation (see figure 1).

默认情况下将不安装ADSync，但可以将它用作可选程序文件之一，因此必须在安装过程中选中它(参见图1)。

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Part D is an optional insurance program that charges a monthly fee in exchange for prescription drug coverage.

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As a compromise, Congress could make the program optional, but give employers who adopt the principles safe harbor from employee lawsuits involving plan investment options.

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This optional monthly payment program, called Fidelity Smart Payment Program, uses quantitative analysis to determine a schedule of annual target payment rates, with a goal of not running out of money before the target date is achieved.

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