根据句子意思，在空格中填写适当的单词，使句子完整、正确。

1. — Can you help me to solve this difficult maths problem?

    — With _____.

2. He is _____. Please give him something to eat.

3. I don't like the colour of this pen. Could you show me _____ one?

4. December is the _____ month of a year.

5. Mary and her friends _____ themselves at the English party last night.

6. His eyesight is too poor. He can _____ see anything.

7. Forty-five minutes is three _____ of an hour.

8. With the help of his teacher, he has already _____ up with his classmates in study.