[单项选择]The population of many Alaskan cities has ______doubled in the past three years.
A. larger than
B. more than
C. as great as
D. as many as

There are stock markets in large cities in many countries. Stock markets in Paris, London, Tokyo, Shanghai and New York are among the largest and most well-known. The stock market, also called stock exchange, is a place where people can buy or sell shares of a factory or a company. And each share means certain ownership of a factory or a company.
Different people go to stock markets. Some are rich, who want to get more money than they have. Others are not rich, who buy stocks and try to become rich. Still others buy stocks as part of their plan to save money. Of course, investing money in the stock market is not the safest way to make money. No one can tell exactly whether the shares will be doing well. The factory or the company may do badly. Then the stocks will go down, and investors will lose money. The stock may go up or down for a number of untold reasons. Everyone wants the stock to go up, but sometimes even if a factory or company does a good job, the stock may st
A. stock markets are not the safest place to make money
B. the factory or the company may do badly
C. the stock may go up or down for a number of untold reasons
D. sometimes even if a factory or company does a good job, the stock may still go down