【正确答案】正确答案：Move-α rule is a general movement rule for all the movement rules, accounting for the syntactic behavior of any constituent movement. In this rule, "a" is a cover term for any element that can be moved from one place to another. It goes like this: any element may be moved to another place, or more generally changed in some way, as long as the relevant conditions(principles)are satisfied. These principles reflect a fact that movement is constrained. It has been shown that only certain categories are targeted by movement rules, and that there are limits on how far elements can be moved. That is to say, there are some other constraint rules in the grammar operating upon movements so as to rule out ungrammatical forms, such as " the kissed boy girl" and "was kissed the girl by the boy". It is the interaction of move-a with other syntactic principles that results in grammatical strings. For example, it is responsible for the mapping between active and passive, which is a NP-movement; between affirmative and interrogative, which is a WH-movement.