You need to replicate a table from a master to a slave. The master and slave copies of the table will have different number of columns. Which two conditions must be true?（）

• A、Each extra column in the copy with more columns must not have a default value
• B、Columns that are common to both versions of the table must be defined in the same order on the master and the slave
• C、The slave database cannot have more columns than the master. Only the master database can have more columns
• D、Columns that are common to both versions of the table must come first in the table definition, before any additional columns are additional columns are defined on either server
• E、The master database cannot have more columns than the slave. Only the slave deatbase can have more columns