Here are some suggestions to fill in the blanks:

2. Children can come to many different centers either before or **after** school, the centers will also be **open** on Saturday and **during** the school holiday summer. With the opening of these **centers**, parents will have a great burden off their minds. They can be sure that their children will be **taken** care of in a clean and safe environment.

3. London is the biggest city in **England**. More than seven million people live and work **there**. London is also **one** of the most important **cities** in the world. It is a center for business and **tourism**.

4. Last week, Jimmy invited me to his birthday party. I spent a long time **thinking** about what I should buy as a present for him. Finally, I decided to buy a clock. I went to the nearby **shopping** center to look for a suitable one. After **finding** it up, Jimmy was very pleased to see me and **thanked** me for the present.