Are any specific requirements on capitalizing While addressing letters?

[sky753]

Hi everyone,

Could I trouble you explain the following 3 questions?

1.Must all the letters on the envelope be capitalized ? Are any specific requirements on capitalizing While addressing letters?

2.Miss Beard didn’t manage to solve the problem _____ her manager had explained how.

A.until B.unless

As regards to questions ,if choose B,how can we revise the question body?

3.Our teacher often refers to the clothes designed by you during our clothing designing class.

Is there anything wrong or improper in question 3,esp in the underlined part?
weiqun ding

[Tdol]

There's no need to capitalise everything on an envelope, Just use captial letter for proper nouns.

2- Miss Beard wouldn't have solved the problem unless ....

3- It could be ambiguous- the 'during...' could mean that the clothes were designed during the class. To remove this, place it at the beginning:
During our clothing designing class, our teacher often refers....