A、Inclusion of appropriate humor. B、Direct statement of purpose. C、Professional look. D、Accurate dating. A短文中提到，用诙谐的语言书写备忘录是备忘录区

(16)There are a few differences in the organization of memorandums and letters. Memorandums and letters differ somewhat in appearance. "To" and "From" replace a letter’s inside address and signature block, for example. Further, letters are usually sent outside the organization, while memorandums are usually internal messages. As internal messages, memorandums tend to be more informal and more direct than their letter counterparts.
     (17)One survey of 800 businesspeople showed they spent from 21 to 38 percent of their time writing memorandums. There must be a lot of executives overwhelmed by the number of memorandums they receive.(18)As a result, competition for the reader’s time places importance on the directness and clarity in memorandums. So perhaps even more so than with letters, memorandums should start with the statement of the purpose early in the message. Memorandums also need special visual treatment: keep paragraphs short, much like newspaper articles. Computers increasingly aid mid- and upper-level managers who prepare their own memorandums without secretarial help. If you prepare your own correspondence, realize the importance of dating your messages. Knowing precisely when you recommended, ordered, signed or asked about something often is crucial. Computers often can date information for you easily.
     (19-1)Another characteristic that can set memorandums apart from letters is the inclusion of humor. When the internal message is lighthearted and relatively unimportant, humor in a memorandum can distinguish its author as a person with personality and depth.(19-2)As long as the humor is on the target, does not embarrass others, is not overdone and is not too frequent, it can reflect positively on its author.
16. How does the speaker start his talk?
17. What did the survey of 800 businesspeople show?
18. What does the speaker say is most important in memorandum writing?
19. What characteristic of a memorandum can make readers think highly of its writer?