Minus-minded managers will give employees permission not to attend if they are not needed.

有减法思维的经理会允许员工不参加不必要的会议。

They will simply not be at the courthouse, and they will not be engaged if they are not needed.

他们根本不在法院，如果不需要，他们就不会参与。

Part of the challenges you have is the distances involved in getting supplies if they are needed from the mainland.

存在的挑战是如果你需要内陆地区提供物资，那距离是个问题。

The news comes as the government announced a new policy to deal with a spike in Delta variant cases to ensure enough hospital beds are available if they are needed.

在此消息公布之际，日本政府宣布了一项新政策，以应对“德尔塔”病毒变种病例的激增，从而确保在有需要时提供足够的医院床位。

There isn't a logic always that we can use to explain why some expressions use " on hand" and some expressions use " at hand." " On hand" often refers to things that are available to use if they are needed.

并不总是有一个逻辑可以用来解释为什么有些表达方式使用“on hand”而有些表达方式使用“at hand”。“On hand”通常指的是在需要时可以使用的东西。