Red is used in many American expressions. It can be used to show happiness, as in the expression “a red-letter（红字母） day”.（大喜的日子） This is a day when something special happens. The expression is probably based on church customs. For almost 600 years, church calendars have been marked with red to show special holy （神圣的）days. Today’s calendars are still marked that way with the dates of holidays and special days printed in red.
    The expression “a red-letter day” is often heard in everyday life. “A red-letter day” is a day that people are especially happy. It may be a day that you have long waited for, a wedding （婚礼）day, for example. Or it may be a day with a happy surprise. You might tell a friend that yesterday was a red-letter day, because you won some money in the lottery.
    “Rolling out the red carpet”（铺红地毯） is another commonly heard expression. It describes an especially warm welcome of any kind. A city may “roll out the red carpet” for its baseball team, when the team arrives home after winning a championship. A group of supporters go to the airport to greet the team. The red-carpet welcome includes a lot of cheering by thousands of fans, a parade, music and speeches of praise by local politicians.（政治家）
    Red is also used in some expressions that are not happy. “Red-handed”（抓个正着） is one. To be caught “red-handed” is to be found in an act of wrong doing. The evidence is clear. You are guilty.（有罪）
    Today we use the expression to be caught “red-handed” in situations that are not serious. For example, a mother might say she caught her son red-handed, taking cookies out of the cookie jar. （容器）