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.