My question arose after I have completed this quiz: https://www.sporcle.com/games/g/common_english_words (I do use Sporcle a lot).
The quiz is amazing and very nice to play. However, a question appeared in my mind: why are some letter strings sometimes treated as two different words but sometimes as the same word? The author indeed did a great job when he/she listed 100 most common English words. But I wonder what criteria he/she used.
For example, look at "they" and "them". Or "she" and "her" et cetera. As you see, the words "they" and "them" occupy two distinct slots.
On the other hand, if you try to enter "am", or "are", or "is" (or "has", "had" etc.) [after you have already entered "be" or "have" respectively], then nothing happens. I guess this is not because these verbs aren't among 100 most popular words (I think they are!) but just because "am", "are" and "is" are treated as forms of the verb "be" ("to be"). But if this is essentially the same word, why isn't it the case for "they" and "them"? The words "they" and "them" clearly have the same basic meaning, they both are pronouns. Also, they have one common initial sound and share three letters in common, out of four total. For comparison, the verb forms "be", "am" and "is" share no identical sounds or letters at all.