1. have no idea

不知道；不清楚

eg. However, I have no idea where to go.

但是，我拿不定主意去哪兒。

eg. Right now, we have no idea of the impact of these drug residues or what we can do about them.

目前，我們還不知道這些藥物殘留會對身體產生什么影響，也不知道該對它們做些什么。

2. ahead of

在…之前

eg. Let's cut through the woods and get ahead of them.

咱們穿過樹林抄近路趕到他們前面去。

eg. He had to work hard to remain ahead of his classmates.

他必須努力學習以保持他在同學中的領先地位。

3. run out of

用完

eg. We ran out of coal,and had to burn wood.

我們的煤用光了，只好燒柴。

eg. As long as the atmosphere has molecules of hydrogen and molecules of oxygen, why should we ever run out of water?

既然大氣中存在著大量的氧分子和氫分子，那為什么還會出現水資源短缺的問題？