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Which is correct: All you need is two nights a week. OR All you need are two nights a week.

marked as duplicate by RegDwigнt Dec 15 '14 at 15:54

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It would be "All you need is two nights a week" because "two nights" is functioning as a period of time as a whole, which makes it singular. It would be plural only if the nights were stressed as individual units, as in "Two nights have passed without anything happening." The same rule applies to money: when it refers to the amount as a whole, it's singular ("Three dollars doesn't buy you much") but when it refers to the individual units, it's plural ("Three dollars were lying on the ground").

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