The little girl was lisping when she said 'seven', pronouncing it as 'theven'.

lisping 是动词 lisp 的现在分词形式。lisp 指"说话时咬舌发音"，特别是发/s/和/z/音时舌头位置不对，导致发音不清或发成/th/音。这种发音现象俗称"大舌头"。