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.