题目

Nowadays, millions ___53___ lonely singles are now going online instead. ___54___World Wide Web is quickly becoming the world’s most popular matchmaker(媒人).     Singles are flocking(涌向) to the Internet___55__(main) because their busy lifestyles leave them little time to look for a significant(重要的) other. Using dating sites(约会网址) is quick and convenient. Many singles say the regular dating scene ___56___(just lead) them from one bad experience to ___57___ and are ready to try something else. Dating sites also make ___58___ easy to avoid someone ___59___ you are若nA为阿伏加德罗常数的数值，下列说法正确的是 A．标准状况下，5.6L CCl4含有的C－Cl共价键数为nA B．2.4g Mg与足量稀硫酸反应时，失去电子数为0.1nA C．l L0.5mol. L－1 CuCl2 溶液中含有的 Cu2+数为0.5 nA D．16g氧气和臭氧的混合物中氧原子数为nA