听力原文： Today I am going to talk about the differences between British English and American English. To begin with, some of the spelling of the British English are really different. Words like theater and center end in re in England instead of in er, the way the we Americans spell them. And color is another more example. In fact, many words, which end in or in American English, are spelled our in British English. However, if someone comes here from England, we can all understand what he is saying. So spelling doesn't really matter that much. Besides, there are some differences in pronunciation and meaning too. I remember seeing an English movie were the actors kept calling their apartment a flat. Haft of the movie was over before I realized what they were talking about. And pronunciation is different. In a word, British English and American English are different, but not so different that is prevents us from understanding each other. According to this passage, how is the word center spelled in British English?