(Boneh-בונה Ep. 58) (#778) To clog a small crack in a pipe. Turning off gas range. Putting on, taking off smoke detector. Unscrewing the bulb that's off.

Various important examples which come up on Shabbos in conjunction with the halachas of perfuming or putting in a nice smell into an item;

understanding the Concept of מבטל כלי מהיכנו (Nullifying a Vessel from Its Usage);

How much time is needed before or after shabbos to say it is "שכר שבת בהבלעה" (shabbos earnings included with weekday earnings).