▎ 摘　　要

The resonant behavior of vacancy states in graphene is well known but some ambiguities remain concerning, in particular, the nature of the so-called zero energy modes. Other points are not completely elucidated in the case of low but finite vacancy concentration. Here we concentrate on the case of vacancies described within the usual tight-binding approximation. More precisely, we discuss the case of a single vacancy or of a finite number of vacancies in a finite or infinite system.