Explanation:   

  In the United States, the president has to be re-elected every four years. The elections take place (or are held) every four years in November. Every U.S. citizen who is at least 18 years old can vote for president (or say who he or she would like to become president).  

 

  U.S. citizens have to register (or sign up) to be able to vote. They need to fill out a voter registration card (or form) with their name and address. With just one voter registration card, you can register to vote in national, state, and local elections.  

 

  On election day, registered voters can go to the voting booth that they have been assigned to (or asked to go to). At the voting booth, they get a ballot, or a piece of paper with the names of people who are running for office (or trying to get a public position).  On this ballot, they indicate (or show) which person they would like to vote for. Doing this is known as casting a ballot. 

 

  In many states, voters are allowed to vote by mail. They don’t need to go to a voting booth. Instead, a ballot is mailed to their home. They need to fill it out and mail it to the correct address by (or before) a certain date to have their vote counted (or included) in the election. U.S. citizens who are living in other countries can also vote by mail. 

 

  Unlike in some other countries, voting is optional in the United States, meaning that people can choose to do it, but they don’t have to. Many people choose not to vote and never fill out a voter registration card. In the 2004 presidential elections, only 60% of eligible voters voted, meaning that 60% of all the people who could vote did. Many organizations try to get more people to register to vote and participate in the elections, because they believe that our government would be stronger if more people voted. 

 

问题：