半杯水是什么哩？
To the optimist, the glass is half full. To the pessimist, the glass is half empty. To the engineer, the glass is twice as big as it needs to be.
對于樂觀主義者，這玻璃杯有一半是滿的； 對于悲觀主義者，這玻璃杯有一半是空的； 對于工程師，這玻璃杯比實際需要打了一倍。