In the green tree (en ugrwi xulwi). Green wood is hard to burn and so is used for the innocent. In the dry (en twi xhrwi). Dry wood kindles easily and is a symbol for the guilty. This common proverb has various applications. Here the point is that if they can put Jesus to death, being who he is, what will happen to Jerusalem when its day of judgment comes? What shall be done (ti genhtai). Deliberative subjunctive.