What do comic book villains have in common (有共同点)? They harm others or break the law to get what they want. Another thing is that they often wear clothes in green and purple colours, and some even have green or purple skin. But why do they wear these colours? Let's find out.

First, let's look at culture and history. In Shakespeare's play Othello, a character warns another about envy and calls it a "green - eyed monster". This is where the saying "green with envy" comes from. However, even before this play, green connected the colour green with negative (消极的) feelings like greed (贪婪). The ancient Greeks believed that when a person was sick, their skin might turn green. Over time, green has come to stand for greed, sickness, and envy — feelings that are often found in villains.

But what about purple? The colour purple is often connected with power. It is not a colour that we see a lot in nature, and in ancient times, purple dye (染料) was very hard to make. This made it rare and expensive, so only the most powerful people could afford it. In ancient Rome, only leaders could wear clothes in purple, and in England, Queen Elizabeth I allowed only close relatives to wear purple. So, when villains show up wearing purple, it suggests they are powerful or think of themselves as powerful. It also shows that they want respect from others.

Now, let's look at colour theory (理论). The three primary colours are red, yellow and blue. If you mix any two primary colours, you get one of the three secondary colours: orange, purple or green. Most superheroes wear at least one primary colour, and some have all three. If heroes wear bright primary colours, comic artists often use secondary colours like green and purple for villains. This way, even if you don't know the story or the characters, you can quickly tell the heroes and villains apart just from their colours.