the glass is half empty idiom
水杯一半是空的（一种看事物或形势时看到更多坏的一面的倾向）
used to refer to an attitude of always thinking about the bad things in a situation rather than the good ones
A pessimist says the glass is half empty but an optimist says that it is half full. 悲观主义者说水杯一半是空的，乐观主义者说水杯一半是满的。