题目

Perhaps you have heard a lot about the Internet，but what is it，do you know？The Internet is a network．It uses the telephone to join millions of computers together around the world． Maybe that doesn't sound very interesting．But when you're joined to the Internet，there are lots and lots of things you can do．You can send E-mails to your friends，and they can get them in a few seconds．You can also do with all kinds of information on the World Wide Web（WWW）． There are many different kinds of computers now．They can all be joined to the Internet．Most of them are small ma在给定条件下，下列选项所示的物质间转化均能实现的是（ ）A. NaCl NaHCO3 Na2CO3B. Cu CuS CuCl2C. Fe2O3 FeCl3(aq)无水FeCl3D. MgCO3MgCl2(aq)Mg