他偶尔进城买补给品。

He went into town ___every ___so ___often to buy supplies.

伊丽莎白和其他人偶尔来看她，直到有一天她离开了他们。

Elizabeth and others visited her ___every ___so ___often until [one] day she left them.

我偶尔检查电子邮件以保持更新。

I check my email ___every ___so ___often to stay updated.