Some structures are formed by joining two or more elements of the same type with the help of a conjunction such as and or or. Such phrases are called coordinate structures and this phenomenon is known as coordination.有些结构是借助于像and或者or这样的连词将同种类型的两个或多个成分连接起来而构成的。这样的短语被称为并列结构，这种现象称为并列。10. coordination rule 【答案】The coordination rule can be formulated as below: X→X*Con X. In this rule, the symbol X stands for ‘a category at any structural level’, indicating that either an X or an XP can be coordinated. The asterisk (*) indicates that one or more categories can occur to the left of the Con (conjunction).