Have you rung up your mother recently?

你最近给你妈妈打过电话吗?

I was rung up by an old friend this morning.

今天上午有个老朋友给我打电话。

To be safe you should go up a ladder one rung at a time.

为安全起见, 登梯子时你应该一步一步往上爬。

Most of the workers had already rung in by the time I arrived.

到我来的时候为止, 大多数工人都已签到了。

Hold the ladder tightly and move up a rung at a time.

抓紧梯子一级一级地往上爬。