MERGE INTO/INSERT ALL/INSERT FIRST

[Xviewee]

一道课后习题：
You need a mechanism to import data into Oracle from a legacy application
and, using a value in one of the columns in the source data, add the row to
one of several tables in your database. Which of the following can you use
to satisfy your requirements? (Choose two correct answers.)
大意是需要一种机制，可以通过使用数据源(某个表)中的一个列的某个值，并且可以在某个表内添加记录。。
A. PL/SQL
B. MERGE INTO
C. UPSERT
D. INSERT
E. INSERT ALL
F. INSERT FIRST

答案是A、F，不过为什么B和E不是。。

[观想]

晕，all-in-one里面的练习题，我也不理解，请高人指点