Complex sentence: She also knew a few compound verbs, such as "put back", although linguists concluded that she was almost certainly treating them as single words in her vocabulary, and learned few stative verbs within the typical time frame of language acquisition.
Split into simpler sentences: She also knew a few compound verbs, such as "put back", although linguists concluded that she was almost certainly treating them as single words in her vocabulary. In addition, she had learned few stative verbs and reportedly did so within the typical time frame of language acquisition.