1) “It’s Always Sunny in Philadelphia” season-opener, 9 p.m., FX and FXX. Last season, the “Sunny” people (shown here) did an “Abbott Elementary” episode, “helping” at the school. Now the “Abbott” people offer extra footage of what happened that day. It’s hilarious… and R-rated. Janine, the gentle grade-school teacher, even manages a harsh word.
2) More “Sunny,” 9:33, FX and FXX. After the opener, “Sunny” is back to its usual form — odd, erratic and, at times, terrific. The big laughs are at the beginning and end. In between? Frank seems to be on his deathbed; the guys flounder, but Dee (Kaitlin Olson) has some good moments.
3) “Abbott Elementary,” 9 p.m., ABC. Oddly, ABC chooses this time to repeat the original “Abbott” episode with the “Sunny” crew. That’s surrounded by more comedies: “Abbott” at 9:30 (the 100th day of the school year), “Shifting Gears” at 8 (Riley finds pot gummies in her son’s pocket) and 8:30 (her estranged husband is back).
4) “Sullivan’s Crossing,” 8 p.m., CW. Last week’s episode veered from joy — Sully’s nemesis is dropping his development plans — to crisis, as Edna suddenly lost her vision. Now comes a fairly good episode, leading to next week’s season-finale.
5) “Human Footprint,” 9 p.m., PBS. Each year, we’re told, people buy 25 billion pairs of shoes. That’s three per human. Many people obsess on them … including host Shane Campbell-Staton, a Princeton botanist and sneaker fan. He has fun, while showing how fashion obsessions have created crises for people, beavers and more.