根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。
While many people are accessible by email, sometimes it is difficult to determine how exactly to write an email to them. Here are some tips for you to follow.
Write an appropriate subject line. The subject line should tell the recipient immediately what the email is about. Remember that your wording also has to be brief.
It is best to be more formal rather than informal, so when writing to someone you have never met or written to before, a "Dear Jane Smith" is appropriate. When addressing someone whom you are a little familiar with, a "Dr. Smith" is okay until they tell you to address them by their first name, in which case a simple "Jane" will be okay.
State your purpose at the beginning. Within the first two sentences of your email, your recipient should know exactly why you are writing to him. Sometimes an introduction may have to precede (先 于) the sentence that states why you are writing and sometimes it has to follow.
Use appropriate language. You may be used to using informal language in certain social settings. Even when dealing with colleagues or friends you are familiar with, do not immediately fall back on informal language.
Keep it simple. People may get dozens and even hundreds of emails a day. In that way, they can save much of their time when reading emails.
A. Use proper greetings.
B. Express your ideas clearly.
C. You should avoid spelling and grammar mistakes.
D. How to Write an Email.
E. Be as specific as possible when writing the subject.
F. However, an email may not be the best place to use such language.
G. It is always easier for them if you keep your email as short and brief as possible.