Because of the construction decline, （） housing is available.A、fewerB、lessC、leastD、more

A postman delivers mail round a housing estate.
　　He does not want to visit the same street more than once, but can pass over the same street corners.
　　On which housing estate is this possible?

请阅读 Passage 1,完成第21~25小题。Passage 1Why has crime in the U.S. declined so dramatically since the 1990s?Economists and sociologists have offered a bounty of reasons, including more police, more security technology, more economic growth, more immigration, more imprisonment, and so on.The real answer is almost certainly a combination of these factors, rather than one of them to the exclusion of the rest. But a new paper adds a surprising variable to the mix. What if the decline of crime in America started with the decline of cash?Cash is critical to the health of an underground economy, because it's anonymous, nearly untraceable, and easily stolen. This makes it the lifeblood of the black market.But Americans are rapidly abandoning cash thanks to credit cards, debit cards, and mobile payments. Half a century ago, cash was used in 80 percent of U.S. payments. Now that figure is about 50 percent, according to researchers.In the 1980s, the federal government switched from paper money to electronic benefit transfers. They didn't switch all at once. They switched one county at a time within states. This created a kind of randomly controlled environment for the researchers, who studied Missouri's counties to establish whether the areas that switched from welfare cash to electronic transfers saw a concurrent decline in crime.The results were striking: The shift away from cash was associated with a sigpificant decrease in the overall crime rate and the specific offenses of burglary and assault in Missouri and a decline in arrests. In other words, the counties saw a decline in specific crimes when they switched away from cash welfare.Perhaps most interestingly, they found that the switch to electronic transfers reduced robbery but not rape, suggesting that the move away from cash only had an impact on crime related to getting and spending cash.The move toward cashlessness in the U.S. continues quickly. Google now lets you attach money to emails to send to friends, which means that for some shoppers, pulling out your credit card could become as rare as finding exact change in your coin purse. It might seem absurd to imagine Visa, Square, and Google Wallet as crime-fighting technologies. But with a better understanding of how cash's availability affects crime, perhaps the government should consider killing more than just the penny.The government switched one county at a time within states favors researchers because ____ .

What does Pine University intend to do by the summer session?

Why are more and more people able to work at home?Because of the increasing use of ____.

According to the passage, the decline of good manners is more worrying because______.

Which of the following is NOT a possible cause of the housing crash?

Centrifugal pumps are popular because they are very simple in construction,and produce smooth, constant, （） discharge.

Because of the construction decline, （） housing is available.

The special needs of old people for housing have _____ more attention from house designers.

The factory had to _____ a number of employees because of the economic decline in the country.

Why is the decline of good manners more worrying according to the passage?