* A: LAST_DAY does not only return the last day of the current month; it returns the last day of the month based on the date argument passed to it, which may not necessarily be the current month. Thus, statement A is incorrect.
* B: CEIL requires a numeric argument and returns the smallest integer greater than or equal to that number. Thus, statement B is incorrect.
* C: ADD_MONTHS function adds a specified number of calendar months to a date. This statement is correct as per the Oracle documentation.
* D: ADD_MONTHS can work with a character string if the string can be implicitly converted to a DATE, according to Oracle SQL data type conversion rules. Therefore, statement D is correct.
* E: LAST_DAY does not specifically return the last day of the previous month; it returns the last day of the month for any given date. Thus, statement E is incorrect.
* F: CEIL returns the smallest integer greater than or equal to the specified number, not the largest integer
* less than or equal to it. Hence, statement F is incorrect.
* G: LAST_DAY returns the last day of the month for the date argument passed to the function, which aligns with the definition in Oracle's SQL reference. Therefore, statement G is correct.