State the difference between the following typewriter ribbons:
1. A red and blue and black ribbon.
2. A red and a blue and black ribbon.
3. A red and blue and a black ribbon.
4. A red and a blue and a black ribbon.
Supply the omitted part in each of the following:
1. I always have and I'm sure I always shall be considerate of others' feelings.
2. They have a stenographer and bookkeeper, who are kept busy all day.
3. I believe he has already or will soon begin the work.
4. The cushions of the rocker are much softer than the armchair.
5. The arrangement of your flat is much more convenient than our house.
6. The number of shelves in your sideboard is just the same as our china closet.