復合介詞in case of

1. 表示條件，意為“如果”“萬一”。如：

In case of fire, ring the bell. 如發生火災，就按鈴。

In case of emergency, break the glass and press the button. 遇到緊急情況時，擊碎玻璃罩并按下按鈕。

In case of my not being here, ask my brother to help you. 如果我不在可讓我弟弟幫助你。

2. 表示目的，意為“以防”。如：

I keep an umbrella here in case of rain. 我在這里放一把雨傘以防下雨。

The wall was built along the river in case of floods. 沿江筑了堤壩，以防漲水。