15. A computer system for teaching a vocabulary, the computer system comprising: one or more processors and one or more computer-readable tangible storage devices; program instructions that are stored on at least one of the one or more storage devices and that, when executed by at least one of the one or more processors, receive a user selection of a chapter from a plurality of chapters in a Chinese-English textbook, the chapter including a plurality of vocabulary words; program instructions that are stored on at least one of the one or more storage devices and that, when executed by at least one of the one or more processors, receive a user selection of a language in which to display questions in a user interface, wherein the language in which to display the questions is one of English, Simplified Chinese, Traditional Chinese, and Pin Yin; program instructions that are stored on at least one of the one or more storage devices and that, when executed by at least one of the one or more processors, receive a user selection of a language in which to receive answers to the questions in the user interface, wherein the language in which to receive the answers is another one of English, Simplified Chinese, Traditional Chinese, and Pin Yin, such that the language in which to display the questions and the language in which to receive the answers are different; program instructions that are stored on at least one of the one or more storage devices and that, when executed by at least one of the one or more processors, determine a question, the question including a vocabulary word of the plurality of vocabulary words in the language in which to display the questions; program instructions that are stored on at least one of the one or more storage devices and that, when executed by at least one of the one or more processors, receive an answer to the question in the language in which to receive the answers, the answer including a vocabulary word; and program instructions that are stored on at least one of the one or more storage devices and that, when executed by at least one of the one or more processors, determine if the answer is a correct answer in response to receiving the answer.
15. A computer system for teaching a vocabulary, the computer system comprising: one or more processors and one or more computer-readable tangible storage devices; program instructions that are stored on at least one of the one or more storage devices and that, when executed by at least one of the one or more processors, receive a user selection of a chapter from a plurality of chapters in a Chinese-English textbook, the chapter including a plurality of vocabulary words; program instructions that are stored on at least one of the one or more storage devices and that, when executed by at least one of the one or more processors, receive a user selection of a language in which to display questions in a user interface, wherein the language in which to display the questions is one of English, Simplified Chinese, Traditional Chinese, and Pin Yin; program instructions that are stored on at least one of the one or more storage devices and that, when executed by at least one of the one or more processors, receive a user selection of a language in which to receive answers to the questions in the user interface, wherein the language in which to receive the answers is another one of English, Simplified Chinese, Traditional Chinese, and Pin Yin, such that the language in which to display the questions and the language in which to receive the answers are different; program instructions that are stored on at least one of the one or more storage devices and that, when executed by at least one of the one or more processors, determine a question, the question including a vocabulary word of the plurality of vocabulary words in the language in which to display the questions; program instructions that are stored on at least one of the one or more storage devices and that, when executed by at least one of the one or more processors, receive an answer to the question in the language in which to receive the answers, the answer including a vocabulary word; and program instructions that are stored on at least one of the one or more storage devices and that, when executed by at least one of the one or more processors, determine if the answer is a correct answer in response to receiving the answer. 20. The computer system of claim 15 , further comprising: program instructions that are stored on at least one of the one or more storage devices and that, when executed by at least one of the one or more processors and in response to determining that the answer is an incorrect answer, increment a value associated with the vocabulary word indicating a likelihood that the vocabulary word will appear in a question.