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Indonesia has said the country would be removing its capital city, in part because it's sinking into the Java Sea. Jakarta is one of the fastest sinking cities in the world, according to the World Economic Forum, due to rising sea levels and the over－extraction of groundwater. But it isn't the only city in trouble. Here's a look at some others that are also at risk.
Houston
Houston has been sinking for decades and, like Jakarta, the over－extraction（抽取） of groundwater is partly to blame.
The Houston Chronicle reported that parts of Harris County, which contains Houston, have sunk between 10 and 12 feet (about 3 meters), since the 1920s, according to data from the US Geological Survey. Areas have continued to fall as much as 2 inches per year, an amount that can quickly add up.
Lawmakers have tried to address the issue, creating a special purpose district meant to regulate the withdrawal of groundwater in 1975. But the problem has persisted（坚持、持续），, with privately owned wells and water suppliers continuing to pull from aquifers(蓄水层)．
Lagos
The city of Lagos sits on the coast of Nigeria, constructed partly on the mainland, partly on some nearby islands. It's also Africa's most populous city. Its geography makes Lagos especially easily flooded, and the coastline has already been eroding. As sea levels rise due to global warming, the city is increasingly at risk.
One study from 2012 revealed that, because Nigeria's coastline is so low, a sea level rise of just 3 to 9 feet(about 1 to 3 meters) “will have a catastrophic effect on the human activities in these regions”．
Washington
Washington is one of the most important cities in the US—and it's also sinking. Research from 2015 showed that America's capital will drop more than 6 inches (15 centimeters) in the next 100 years.
But unlike Jakarta, Washington's sinking has nothing to do with aquifers or rising sea levels—it's actually because of an ice sheet from the last ice age. A mile－high ice sheet pushed land beneath the Chesapeake Bay upward. When the ice sheet melted, thousands of years ago, the land settled back down. The researchers now believe that the area is gradually sinking, a process that could last thousands of years.
21. What is the common reason for the sinking between Houston and Jakarta?
A. The soft land.
B. Rising sea level.
C. The eroding coastline.
D. Over－extraction of groundwater.
22. What does the writer's attitude towards the result of Houston lawmakers addressing the sinking problems?
A. Positive. B. Indifferent.
C. Unknown. D. Negative.
23. Which of the following sinking cities has a clear different reason with others?
A. Houston. B. Lagos.
C. Washington. D. Jakarta.
