In addition to having specific interrogative words equivalent to the English interrogatives such as Who?, Where? and When?, there are three ways to form a question in Spanish. One way is to invert the order of subject and verb. Our declarative or indicative statement Ellos nadan can become a question simply by saying ¿Nadan ellos? In writing, the question is marked at the beginning with the upside-down question mark and closed just as in English with the right-side up one. In speaking, also as in English, the voice tends to rise at the end of a question.
Another way to turn the statement into a question in Spanish is to simply use the rising tone without changing the word order: ¿Ellos nadan? This method of question formation can create a tone of incredulity or even sarcasm.
Finally, there is the tag question. A tag question is one that makes a statement and follows up with a quick question, almost like an afterthought. The most common tags are ¿no? and ¿verdad? In writing, the tag question is Ellos nadan, ¿no? Notice the way in which the statement is separated from the tag question by a comma and that the question only is framed with the written question marks. With tag questions, the initial statement is still stated as a declarative, that is, with a slightly falling tone as the word nadan is pronounced. The tag question ¿no? is pronounced with a rising tone.
The quizzes to this lesson will present you with statements which you are to convert into two kinds of questions: the first type, inverting subject and verb, and the tag questions. The option of simply pronouncing the statement as a question cannot really be tested in writing except for framing it with the question marks!