Social network sites are usually free to join.
社交网站是免费加入的。
People e's opinions vary greatly on social network sites.
人们对社交网站的看法有很大区别。
But some people don't approve of the social network sites.
但有些人不认同的社会网络网站。
But some people don't approve of the social network sites.
但是有些人不赞成社交网络网站。
However, opponents think it is difficult to protect users' privacy on social network sites.
然而，反对者认为很难保护用户隐私的社交网络网站。
However, opponents think it is difficult to protect users' privacy on social network sites.
然而，反对者认为很难保护用户隐私的社交网络网站。
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