2--Do you see that couple over there?
 
1--Yeah, it looks like they are going into that new restaurant. They look great!
 
2--Oh, yeah! They are dressed to kill.
 
1--In American English, "dressed to kill!" is a different way of saying "dressed very attractively" or "dressed to impress."
 
2--This phrase came from criminals...
 
1--In the past, people who were professional criminals often dressed in fancy clothing to hide the fact that they were doing horrible things.
 
2--So, if you were "dressed to kill" back then, you would be wearing a pretty nice looking outfit.
 
===================================
注解：
 
1.opposite相反的
2.impress给…留下深刻印象 
3.professional专业的

===================================
译文：

1--您听过某人说“dressed to kill（穿好衣服去杀人）”么？别担心，没有什么危险——而恰恰相反。
2--你看见那边那对夫妇了么？
1--是的，他们好像是要去那家新餐厅。他们看起来漂亮极了！
2--哦，是的！他们穿得好看极了！（ dress to kill）
1--在美语中，“dress to kill”（穿得美极了）是“dressed very attractively”和“dressed to impress”另外一种说法。
2--这个短语来源于犯罪分子……
1--过去，专业的罪犯总是穿着光鲜亮丽的衣服，用以掩盖他们在做坏事。
2--所以，在过去如果你是“dressed to kill”（准备实施犯罪活动），你应该穿上非常漂亮的套装。