双宾语动词 变疑问句

解题思路： 如下
解题过程：
The waiter taught him a few words of Italian. 同义句
The waiter taught a few words of Italian to him.
teach 后面跟的双宾语，him为介词to 的宾语。划线提问的时候，to 不能省略，另外特殊疑问词用Whom 更好，Who这个疑问词/代词的宾格。Whom 比 who更为正式。在口语中WHO可以做主语，也可以做宾语。
Whom did the waiter teach a few words of Italian to ? 这个答案更完美，我认为。你说的括号中的TO 要保留。
再如 Who /Whom did you give the pen to ?
To whom did you give the pen ? （介词To放在句首时，只能用WHOM）
明白了吗？
最终答案：略