用所给单词的适当形式填空。
1. December is the ________ (twelve) month of a year.
2. As we all know, the silk dress feels ________ (soft).
3. She said to the twins, "Help ________ (you) to some fruit."
4. You should do your homework as ________ (careful) as your sister.
5. The foreign teacher gave us some ________ (advice) on how to learn English.
6. _______ (teach) high school students in a poor mountain village may not sound like fun to you.