in case (sth happens) · if · once (sth happens, then...) · when · in a short time · in one day

China is a sleeping tiger, but once it wakes up, it will shock the world.

All humanity will suffer if a nuclear war breaks out.

All individuals in the world act with clear goals and distinct intentions. But once these actions are brought together by the great torrents of life, clarity recedes and chaos ensues.

A bad habit, once formed, is difficult to get rid of.

Once you have formed a bad habit, you can't get rid of it easily.