题目

NASDAQ, standing for the National Association of Securities Dealers Automated Quotation system, is one of the largest markets in the world for the trading of stocks（股票）. The number of companies listed on NASDAQ is more than that on any of the other stock exchanges in the United States, including the New York Stock Exchange (NYSE), and the American Stock Exchange (AMEX). The majority of companies listed on NASDAQ are smaller than most of those on the NYSE and AMEX. NASDAQ has become known as the home of new technology companies, particularly computer and computer-related busines 由电场强度的定义式E＝F/q可知，在电场中的同一点 　 A．电场强度E跟F成正比，跟q成反比 B．无论检验电荷的电量如何变化，F/q始终不变 C．一个不带电的小球在P点受到电场力为零，则P点的场强一定为零 D．电场中某点的场强为零，则在该点的电荷受到的电场力一定为零