С какой целью употребляется указательное местоимение в сложноподчиненных предложениях?

помогите сделать:

Задание:

What is going happen? Write it down.

1. Linda has a toothache. She (see) the dentist

   .................

2. They decided to arrange a picnic. They (have) a nise time.

   .................

3. Andrew has a little sister. His parents are busy today. He (stay) with his sister.

   .................

4. it's the weekend. It's sunny and warm. We (waik) in the park.

  .................. 

5. Some British stdents would like to come to Rossia in October.We (invite) them.