Complex sentence: Among the evidence for this analysis is that some suffixes have suppletive variants for monosyllabic and bisyllabic bases; stems which appear monosyllabic and begin with a consonant in fact select the bisyllabic variant.
Split into simpler sentences: Among the evidence for this analysis is that some suffixes have suppletive variants for monosyllabic and bisyllabic bases. Stems that appear monosyllabic and begin with a consonant in fact select the bisyllabic variant.