Normally the Treasury tries to maintain a balance of at least $500bn, enough to cover about a week of cash outflows.

正常情况下，财政部将余额保持在至少5000亿美元，足以覆盖大约一周的现金流出。

So there are times where your cash outflows exceed your cash intake, and there, you need some form of credit to make up that difference.

因此， 有时您的现金流出会超过您的现金摄入，此时您需要某种形式的信贷来弥补这一差额。