选用所给单词的适当形式填空 （每次限用一次）

shelf,  sit,  twelve,  friend, we,  good

 
December is the _______ month of a year.
At weekends, we often watch TV in the _______ room.
Nancy doesn’t dance _______.
There are many books on these _______.
My neighbours are very _______ to us.
Let _______ help you.