备用 (bèi yòng): Reserve (Verb) — Meaning & Stroke Order

Before traveling abroad, it's best to exchange some foreign currency in advance for backup.

Are you sure this backup plan is truly without any risk of failure?

Although there was a backup plan, the team ultimately did not launch it.

I'll give you the spare key to keep, just in case I forget mine.

He secretly gave the spare key to his friend, which made me very angry.

After receiving the power outage notification, we immediately prepared a backup power source.

If there is a traffic jam, do we need to meet at the alternate location?

I usually keep a spare charger in the office just in case.

Hearing that the subway was going on strike, I quickly checked for alternative travel plans.