You can use the data dictionary USER_UPDATABLE_COLUMNS view to find out which of your view columns are updatable.
The following code shows that you cannot do much with the DESCRIPTION column of the CRS_OFFERINGS view.
SQL> SQL> select column_name 2 , updatable, insertable, deletable 3 from user_updatable_columns 4 where table_name = 'CRS_OFFERINGS'; no rows selected-- www. j a v a2s. c om SQL>