The Harry Potter books are quite popular; they are in great ______ in this city.

People are using more and more natural gas, wind and other forms of _____.

 David had prepared carefully for the exam so that he could pass it at his first ________.

As is known to us all, our Chinese government is now making every         to stop the house price from growing too fast.

 Due to the unreasonable individual income ­_______, the gap between the rich and poor has become an outstanding issue.