Berachos 3a - Part 1

The gemara asks that R' Meir seems to contradict himself in the baraissos. In one baraissa he said "the time of eating erev shabbos" and in the other he said "the time of tevilah". The gemara answers that it is a machlokes tannaim what R' Meir held.

The gemara further asks that R' Eliezer seems in contradiction. One time he said "from the time of kedushas hayom of shabbos" and in the mishna he seems to agree that it's "from the time the kohanim enter to eat terumah". Again, the gemara answers it's a machlokes tannaim what R' Eliezer held. Alternatively, the gemara answers that R' Eliezer actually did not agree with the first part of the mishnah.