Shabbat 17

Today's shiur is dedicated for a refuah shleima for Eliezer Yehuda ben Chaya and Rivka Chaya bat Leah and by Elizabeth Kirshner in honor of the Hadran community and in honor of her inspiring and strong mother, Debbie Kirshner-Devries and for a refuah shleima for Avigayil bat Dina. A special mazel tov to David Schwartz who is celebrating his bar mitzva this morning (virtually) and this coming Shabbat.  

The gemara discusses more of the 18 ordinances. 1. Moveable items bring impurity if they are thickness of an ox goad. What exactly is this? There is a difference of opinion. 2. One who harvest grapes - the liquid that seeps out of them renders the grapes susceptible to impurities. Several explanations are brought to explain why they instituted this. 3. If teruma is replanted, what grows is also teruma. 4. If one was carrying a wallet and Shabbat started, one should give it to a non Jew rather than carry it in increments less than 4 cubits. 5. The bread, oil wine and daughters of non Jews are forbidden. If one adds the previous list - 10 relating to impurities mentioned in daf 13 and one who leaves water under a pipe/gutter and the Kutim are considered nidda from birth and one can't take lice off clothing or read by candlelight, the count becomes 19, not 18. How is this reconciled? (Others get to 19 from a different count. 10 from daf 13, 4 mentioned above, bread, oil, wine and daughers of non Jews are counted as 4, gentiles are all considered zavim, numbers 1-4 mentinoed above and water under the gutter). The mishna brings a debate between Beit Shamai and Beit Hillel regarding shvitat keilim. Can one start a melacha before Shabbat if the melacha will continue after Shabbat starts even if it is done on its own, without human intervention?