Ответ:

Используем there is / there are, чтобы сообщить о наличии предмета или людей, а it is / they are, чтобы рассказать о уже названном предмете или людях.

  1. There is a letter on your desk. It is from your uncle.
  2. There are some people in the office.
  3. “Where’s my football?” “It is in the garden.”
  4. Look! There is a beautiful rainbow in the sky.
  5. There are two parks in this town. They are quite big.
  6. There is a box on the desk. It is Laura’s.