下列四种物质的组成排列中，合理的一组是（   ）

以下是利用更相减损术求78，36的最大公约数的操作步骤（78，36）→（42，36）→（6，36）→（6，30）→（6，24）→（6，18）→（6，12）→（6，6）那么78和36的最大公约数为（　　）

    The Internet ____(become) part of young people’s life already. A report shows that 38%  of students often use the Internet .  Most  of  them get ____ (use) information on the Internet ____use the Internet to help their studies. But many students don’t use it ____a good way. Some play games too much, some visit websites that____shouldn’t look at. So bad things may happen____students spend too much time on the  Internet.

    ____ is important for students to use the Internet properly. Now we have a textbook,____uses many examples to teach students some good ways to use the Internet. It gives useful ____ (advise).

    Some students also make friends on the Internet.  But  if you want to have  a face-to-face ____ (meet) with your online friends, let your parents know and meet in a proper place.