Barry Epstein asked:

Why does the word vehaavarta render the gezeirah shavah between maaser and bechor impervious to refutation? I don't understand how a word locks up a gezeirah shavah.

Barry Epstein, Dallas, TX

The Kollel replies:

A Gezeirah Shavah in which the word used for the Gezeirah Shavah is extra (not used to teach anything else) is irrefutable. Seemingly, this is because the reason the Torah uses this word is only in order to make it comparable to the other place where the word is written. If the words are the same but not extra, then we learn the Gezeirah Shavah but it can be refuted.

D. Zupnik