The difficulty with "That is" is you are referring to by yourself within the 3rd individual. Great for introductions of another person, although not yourself. Say "I'm Joe Doe" or "You've reached Joe Doe" or even just "Joe Doe". We're about complicating something that is very very simple. “Good 词汇”：相关单词和短语 https://online-case-study-solutio62460.blogunok.com/39802423/affordable-case-study-solution-no-further-a-mystery