Bisher habe ich folgendes geschrieben:
Complementizer Phrases (CP) are subordinate sentences with a complementizer and questions.
CPs are headed by a complementizer (that, for, whether, because, which…). Spec., CP is the position for moved elements like wh-words: question formation. Spec, CP is the position for moved elements: wh-movement and auxiliary inversion. CP (Complementizer phrase) is the landing site for movements, specifier. CPs are headed by a complementizer.
Movement operations create trace positions. Movements leave behind traces. These trace positions cannot be reoccupied.
In transformational grammar, a trace is an empty category that occupies a position in the syntactic structure. In some theories of syntax, traces are used in the account of constructions such as wh-movement and passive. Traces are important theoretical devices in some approaches to syntax.