Megillah 30b - Rashi: Question From Ta'anis is Only on R' Yirmiya

The gemara asks: "On Ta'anis (that falls on monday or thurs.) why do we stop reading the parsha of the week, we can read the parsha of the week in the morning and the Ta'anis reading in the afternoon?" Rashi comments that this question is only according to R' Yirmiyah who says that we try to incorporate the parsha of the week together with the special reading on the 4 parshiyos, so we should do the same here. But acc. to R' Ami that we interupt the parsha of the week and substitute if with the 4 parshiyos, we can skip the parsha of the week here too.

Lulei divrei Rashi: I would like to suggest that this question can even be acc. to R' Ami. The reading of the parsha on shabbos is not called the inyana d'yoma, rather it is the seder haparshiyos in order to finish the entire torah in a year (that is why bnei ma'arava could institute a different system to finish in 3 years). But, once there is a parsha that is going to be read on shabbos, portions of that reading are automatically considered inyanan d'yoma on monday and thurs. [see Rashi 22b (d.h. sh'ani) that to extend the reading of monday and thurs. and read more pesukim of that parsha also qualifies as inyana d'yoma]. Therefore, even acc. to R' Ami that we push off the shabbos reading for the 4 parshiyos, that is only bec. the shabbos reading is not inyana d'yoma, but the mon./thurs. reading from the section that will be read on shabbos is considered inyana d'yoma. So even acc. to R' Ami the gemara can ask that we should incorporate both the parsha of the week and the Ta'anis reading.