Impossible 和 unattainable 這兩個英文單字都表達事情做不到的意思，但它們的側重點不一樣。Impossible 強調某事根本不可能發生，違反自然規律或邏輯，通常指物理上或邏輯上的不可能。Unattainable 則強調某事很難達成，即使付出巨大努力，也可能無法實現，它更側重於實際上的困難和限制。

例如：

• It's impossible to travel faster than the speed of light. (超越光速旅行是不可能的。) This sentence describes something that violates the laws of physics.

• It's impossible for a human to fly without the aid of a machine. (人類不借助機器飛行是不可能的。) This sentence describes something that is logically and physically impossible.

• Becoming a billionaire is an unattainable goal for most people. (對大多數人來說，成為億萬富翁是一個無法達成的目標。) This sentence means that while it's not logically impossible to become a billionaire, it's extremely difficult for most people to achieve.

• She found her dream job unattainable due to the fierce competition. (由於競爭激烈，她發現理想的工作無法達成。) This sentence highlights external factors that make achieving the goal difficult.

總而言之，impossible 指的是根本做不到，而 unattainable 指的是很難做到，即使努力也可能做不到。 選擇哪個詞取決於你想表達的具體含義。

Happy learning!