回複：請教一個有關國籍的問題!!!

Legally, U.S. does not recognize dual citizenship. However in practice, dual citizenship is permitted. It's b/c citizenhship is not only governed by U.S. law, it's also governed by foreign law, for example, since 1977, Canada has permitted dueal citizenship. Many European countries, like France, Italy, U.K. also permit dual citizenship. So you get U.S. citizenship, but Canadian government permits you to keep Canadian citizenship.