sen = "A fawn was racing in the forest!He was ahead of the rabbit?He
was ahead of the elephant."
nlp = spacy.load('en')
nlp.add_pipe(nlp.create_pipe('sentencizer'), first=True)
doc = nlp(sen)
sentences = [sent.string.strip() for sent in doc.sents]

"A fawn was racing in the forest!"

"He was ahead of the rabbit?"

"He was ahead of the elephant."