Complex sentence: By contrast, function words such as pronouns, numbers, and words referring to universal concepts, are usually not borrowed, but have been in some cases (e.g., English "they" from Old Norse').
Split into simpler sentences: By contrast, function words such as pronouns, numbers, and words referring to universal concepts, are usually not borrowed. These functionary words are borrowed only in rare cases such as: (e.g., English "they" from Old Norse').