People always shake hands and say “How do you do?” when ______ to_英语解答

People always shake hands and say “How do you do?” when ______ to each other.
A.introduced B.introducing C.to be introduced D.to be introducing
为什么

人气：435 ℃　时间：2019-10-14 00:50:16

解答

应该选A.
完整的句子是：
People always shake hands and say “How do you do?” when they are introduced to each other.
意思是：被介绍给别人的时候,人们经常会摆着手说：”.
这里省略了they are,直接填introduced就行.