The phrase "you are a lucky dog" is a common English expression that conveys the idea of someone being fortunate or blessed. While it might seem like a literal translation of "你是个幸运儿," the nuance in English adds an extra layer of meaning. In English culture, calling someone a "lucky dog" can sometimes carry a hint of envy or admiration, depending on the context.

To express this sentiment more directly and warmly, you could also say "you're so lucky" or "you're a very fortunate person." These alternatives maintain the positive tone while keeping the message simple and clear. The choice between these phrases often depends on the situation and your relationship with the person you’re addressing.

In written communication, such as emails or messages, you might want to soften the expression further by adding a friendly tone, like "I think you're incredibly lucky!" This approach not only translates the original sentiment but also enhances it with warmth and sincerity.

By understanding these variations, you can choose the most appropriate way to convey the idea of being lucky in English, ensuring that your message resonates well with its intended audience.