The concept of strategy derives from the Greek term “strategia” which means generalship or the art of war. In nonmilitary settings, it means a plan, step, or conscious action toward achievement of an objective (Oxford, 1990). Researchers, such as O’Malley & Chamot (1990), Oxford (1990), Wenden (1991), Ellis (1994), and Cohen (1998), have contributed greatly to the development and application of learning strategy theories. However, in educational settings, it has been variously described as “fuzzy” (Ellis, 1994), “no consensus” (Wenden, 1991), and “conflicting views” (Cohen, 1998). Certainly, a brief review of literature will indicate the plethora of different terms for strategy, such as “techniques”, “tactics”, “potentially conscious plans” and so on. There is little consensus regarding what a strategy is. Defining strategy is a difficult task and each definition will cause the controversial views easily. Researchers always emphasize this or that aspect of learning strategies when rendering the definition. For example, Brown (1994) holds the view that strategies are referred to as specific methods of approaching a problem or task, modes of operation for achieving a particular end, or planned designs for controlling and manipulating certain information. However, Ellis (1994) proposes that strategies consist of mental or behavioral activity related to some specific stage in the overall process of language acquisition or language use. Cohen (1998) defines strategies as the process consciously selected by learners. From the above definitions, it could be noticed that Brown tends to define strategies just as behavioral actions. However, Ellis emphasizes both the mental and behavioral aspects. Cohen mainly focuses on the element of consciousness when rendering the definition, which is not mentioned by Brown and Ellis. The writer would like to define strategies as both mental and behavioral actions consciously selected by learners when solving the problems in this study. Learning strategies and language learning strategies Learning strategies have considerable potential for enhancing the process of learners’ language learning and help learners know how to learn more meaningfully, successfully and automatically. Same problems exist when researchers define learning strategies. Different researchers emphasize different aspects of learning strategies. For example, Weinstein & Mayer (1986) hold the view that learning strategies are the behaviors and thoughts that a learner engages in during learning which are intended to influence the learner’s encoding process (Cited by Ellis, 1994); however, Oxford (1990) expands the definition as specific actions taken by the learner to make learning faster, more enjoyable, more self-directed, more effective, and more transferable to new situations; Cohen (1998) defines it as the conscious thoughts and behaviors used by learners with the explicit goal of improving their knowledge and understanding of a target language. Language learning strategies are language specific. Thus the writer of this study is more likely to define learning strategies as behavioral and mental actions consciously selected by learners during learning process. And language learning strategies are behavioral and mental actions consciously selected by learners during language learning process. Classifications of learning strategies Different scholars classify learning strategies from different angles and a large number of classifications exist. In the following part, the more comprehensive and elaborate classifications will be discussed, including O’Malley & Chamot’s and Oxford’s classifications.>