We must find a dictionary. ____       will do.

(2013·陕西咸阳二模)Listening to music can be very enjoyable, but ________ can be appreciated unless you like it.

I have two pens. One is red, and       is blue.

I prefer a house in a mountain village to________in such a large city as Changsha.

 There are over 100 night clubs in the city, but you don’t often see      that is empty.