Błędnie: You can always tell if she's upset or anxious. She bites the inferior lip and clenches her fists. Poprawnie: You can always tell if she's upset or anxious. She bites the lower lip and clenches her fists.
"Dolna warga" to 'lower lip', "górna warga" to 'upper lip'. 'Inferior ' oznacza "niższy", ale w znaczeniu "gorszy, podrzędny".