Formal letter techniques! Crossword

What does the first 'de' in a de:de sentence stand for?
Don't, it's, haven't and can't are all examples of...
Frequently, secondly, after only three days are all examples of...
What technique are brackets, commas and dashes often used for?
Which side of the page does the reader's address go?
Highly-reputable, well-constructed and state-of-the-art examples of what kind of word?
What kind of questions are sometimes used in formal letter writing?
What 'P' is a more formal word for 'bought'?
A different topic is usually introduced at the start of a new...
What 'T' is the name of an introductory sentence?
What do proper nouns, including 'Apple' (the company) always need to begin with?
What does the second part of a de:de sentence (after the colon) give?
The address of the person writing the letter goes on the...
When you do not know the reader personally, the letter is signed off with 'Yours ________'