设a，b＞0，$A=\sqrt{a}+\sqrt{b}$,$B=\sqrt{a+b}$   ，则A，B的大小关系是(    )

阅读下面短文，在空白处填入 1个适当的单词或括号内单词的正确形式。

    In recent years many TV shows have become extremely popular among Chinese audience. Those programs, ranging from talent or dating shows to reality shows ____(receive) both commercial success and public attention.

    Their popularity is ____(main) based on simple facts. First, they care ____social concerns. Second, without exception, they explore a perfect balance between the international forms and Chinese expressions.

    Despite apparent highlights, much room ____ (leave) for improvement. Above all, commercial interests often outweigh ____（education） purposes, causing many complaints about the ____(bearable) advertisements. In addition, some sharp remarks, ____they are eye-catching, may have misleading effects on the youth.

    In my opinion, such shows should shoulder more responsibility instead of merely ____(entertain) the public. ____ is expected, these programs should be positive in their forms as well as functions. Meanwhile, the ____ (medium) should also safeguard the values of our society.

2013年3月1日，QQ登录框启动“画卷·中国”主题活动，陆续推出中国不同地域的自然风情和人文美景画面。3月20日，福建土楼图片亮相腾讯QQ登录界面。回答下题。
下图是QQ登录界面，图中福建土楼主要分布在我市的