Understanding the type of knots that are allowed to be opened on Shabbos.
How and when is one allowed to squeeze or suck the juices from fruits straight into one's mouth.
Introduction to the Melacha of Plowing. Part #2;
ודבר דבר (Dabair Davar): Hinting to Someone to Do an Action After Shabbos Which Is Not Allowed to Be Done on Shabbos;