A: Because memos are standard  forms of communication in many organizations, they "may   become the most common type of business　communication medium.Good memos share  some characteristics.
B: I agree with you.Memos should contain guide-word headings, helping readers immediately  identify  the  date, origin, destination, and purposes of messages.
A； Good memos also generally discuss one topic. Limiting the topic helps the receiver act on the subject and file it correctly.
B: The tone of interoffice memos is expected to be   conversational because the communicators are usually familiar with one another. This means  the occasional use of contractions and first person pronouns.
A：Be aware, however, of graphic highlighting.