This method requests all server updates since the last successful sync and then updates the local database by creating, replacing, or deleting local contacts.

该方法将请求自最后一次成功同步之后的所有服务器更新，然后通过创建、取代或删除本地联系人来更新本地数据库。

youdao

Then I began trawling through old contacts saved on my phone, even the ones that are only there because I never got around to deleting them.

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