Complex sentence: Within the next month Genie's vocabulary acquisition began to accelerate at a progressively more rapid pace, and by March 1971 she was learning new words far faster than any of the hospital doctors had anticipated.
Split into simpler sentences: Within the next month, Genie's vocabulary acquisition began to accelerate at a progressively more rapid pace. By March 1971, she was learning new words far faster than any of the hospital doctors had anticipated.