When she knew (epignousa). Second aorist (ingressive) active participle of epiginōskō, to know fully or in addition (epi), to recognize. She knew Peter and his voice from his frequent visits there.
For joy (apo tēs charās). From her joy (ablative case), life-like picture of the maid who left Peter standing outside with the door to the passageway unopened. Note the aorist tenses for quick action (ouk ēnoixen), eisdramousa (from eistrechō, defective verb, only here in the N.T.), apēggeilen.
Stood (hestanai). Second perfect active infinitive of histēmi, intransitive, in indirect assertion with ton Petron (Peter) accusative of general reference. The slave girl acted as if she were a member of the family (Furneaux), but she left Peter in peril.