What is the difference between (1) and (2)?

题目

What is the difference between (1) and (2)?
What is the difference between "to " and "do" in this sentence?
1)My job duty is teaching customer how to use the Computer System.
2)My job duty is teaching customer how do use the Computer System.

答案

（1）第一句是我的工作职责是教客户如何使用计算机系统
（2）第二句是我的工作职责是教客户计算机系统是如何运作的
两个句子中表语从句的主语是不一样的.第一句是客户,第二句是计算机系统