额外的供应品将会备在手边，以备需要时使用。

Extra supplies will be ___on ___hand, in case they are needed.

从他们的角度来看，他们总能让你随时待命，每当需要帮助时。

From their point of view, they can always have you ___on ___hand whenever they need help.

经理确保在活动期间有一名技术员在场。

The manager ensured that a technician was ___on ___hand during the event.