Question

In Tosafot on Tractate Sukkah 2b, they ask: according to Rava, for whom it is enough that one could make it temporary, if so, why are rains considered a sign of curse on the Festival? After all, one could fasten the boards with nails so that rain would not come into the sukkah. And I did not understand, because in a case of rainfall he cannot make it temporary even with the sukkah covering, since the sukkah would be invalid because of its dwelling conditions. So here too permanent construction would be required.