When translated into English, this sentence means - Is Valentine's Day on January 13? To which obviously you would answer - No, it's on February 14. In Spanish, it would look like this - No, el Día de San Valentín es el catorce de febrero.
The question "¿El Día de San Valentín es el trece de enero?" means "Is Valentine's Day on January 13?" The correct answer is no, as Valentine's Day is celebrated on February 14. In Spanish, you would respond: "No, el Día de San Valentín es el catorce de febrero."
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