Here are the correct forms to fill in the blanks:

1. It is my great **pleasure** to meet you at this important meeting. (PLEASE)
2. I wonder why you are so **familial** with those easy expressions. (FAMILY)
3. There are some **differences** between the two programs. (DIFFER)
4. Good **preparations** were the key to the success of the last Asian Games. (PREPARE)
5. **Environmentalists** are doing their best to save the species from dying out. (ENVIRONMENT)
6. Traveling to the countryside is becoming **increasingly** popular nowadays. (INCREASE)
7. It is education that helps with the **breadth** of knowledge for the young. (BROAD)
8. They were quite **entertained** at the party last night. (ENTERTAIN)
9. Parents should choose **educational** software for their children to use. (EDUCATE)
10. It was another **successful** attempt; they had to try again. (SUCCEED)