若非零向量$\overrightarrow{a}$,$\overrightarrow{b}$满足|$\overrightarrow{a}$+$\overrightarrow{b}$|=|$\overrightarrow{a}$-$\overrightarrow{b}$|=2|$\overrightarrow{b}$|，则$\overrightarrow{a}$+$\overrightarrow{b}$与$\overrightarrow{a}$-$\overrightarrow{b}$的夹角是____ 

完形填空

    I've got some information for everyone who is going to Britain next month. As you know, you are  1  with a family for two weeks. Now the most important thing is  2  . You should take about ￡30 in cash(现金) and about ￡200 in traveler's cheques(支票). Then when you  3  at the airport you'll meet your host family. You must remember to wear a red shirt so the family will find you  4  . I've told them to look for the red shirt. You'll also  5  to take with you four photos of yourself.  6 is very important for you to take the school letter. While you are there,  7  you have any problems, you can call our agent(代理人). I'll give you her office  8 now. It's 580-4436 and the person to ask for is Mrs. Belcher. She's in the office  9  9 am to 5 pm every day. OK! That's everything. Enjoy 10  during the stay in England.

判断下面的说法是否正确

“山”的声母是“s”，而不是“sh”。  (    )

《国家贫困地区儿童发展规划（2014-2020）》强调，对集中连片特殊困难地区农村儿童的健康和教育，要从出生开始到义务教育阶段结束，实施全过程的保障和干预。这体现了对未成年人的（）