It's a rolling contract that could continue, but Mr. Chan has no idea where that will lead.

这是一份滚动合同，可以延期，但是Chan先生不知道结果到底会怎样。

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He also suggested taking out a 30-day rolling contract which is easier to tweak as usage becomes more habitual.

BBC: Counting data cost on mobile phones

In September 2009 he signed a new 12-month rolling contract and took on the title of manager rather than first-team coach.

BBC: Manager Paul Trollope sacked by Bristol Rovers

Former England and Liverpool midfielder McMahon has penned a 12-month rolling contract.

BBC: McMahon signs new deal