Electronic communication, due to its speed and broadcasting ability, is fundamentally different from paper-based communication such as letters and memos.(51)the other person's response time capability is(52)fast, email is more "conversational" than traditional methods of communication.
In a paper document, it is absolutely(53)to make everything completely clear and unambiguous because your audience may not have a chance to ask for(54). With email documents, however, your(55)can ask question immediately. Email, therefore like conversational speech, tends to be much informal and more ambiguous.
This is not always bad. It might not be a(56)expenditure of energy to slave(57)a message, making sure that your spelling is(58), your words eloquent, and that your grammar and punctuation are(59)reproach, if the point of the message is simply to inform. the recipient that your are ready to go to lunch.
Granted, you should put some effort into ensuring that your subjects(60)with your verbs, words are spelled correctly, avoid the mixing of metaphors, and so on.
Because of the(61)of vocal variation, gestures, and a shared environment, email is not as(62)a communication method as a face-to-face or even a telephone conversation. Your recipient may have difficulty(63)if you are being serious or joking, frustrated or euphoric. Thus, your email compositions should be different from both your speech and paper compositions.
With email, you cannot(64)anything about your correspondent's location, time, mood, marital(65)or age, This means, among other things, that you need to be very, very careful in phrasing your communications in order to prevent misunderstanding.

A. Because
B. Although
C. Whereas
D. When