若等差数列{a_n}满足a₇+a₈+a₉＞0，a₇+a₁₀＜0，则当n=____时，数列{a_n}的前n项和最大．

Hi, everybody!
    Welcome to our newly-opened Richards Cinema Bookstore!
    Now let me introduce to you some of the new film books in our store.
Are you Chinese film fans? OK, here comes the latest 25 New Takes about Chinese films. It is a collection of 25 fresh readings of different Chinese films from the 1930s to the present. In recent years, Chinese films are very popular in the States, such as Crouching Tiger and Hidden Dragon, Hero, and Flowers of Shanghai.
    Do you like French films? Well, here is The French Cinema Book. It covers French films from the 1890s to the beginning of the 21st century. It is written for all lovers of French cinema: students and teachers, specialists and fans, and so on.
    Maybe you are Indian film fans and star-chasers. Then here is Encyclopedia (百科全书) of Indian Cinema. The book is a complete introduction to all the best Indian films. It also offers a full list of names of the famous and successful film stars in the past ten years. You know, the Indian film industry is the largest in the world after our Hollywood.
    If you like British films, we have The British Cinema Book. It is a good review of British cinema. This book contains a good many nice pictures.
    In our bookstore, you can also find books about Mexican, Japanese, Australian, German and Italian films.
Well, please help yourselves to some coffee or tea, and have a good time here!

已知AB为⊙O的直径，OC⊥AB，弦DC与OB交于点F，在直线AB上有一点E，连接ED，且有ED＝EF.

如图，在矩形ABCD中，AB=3，对角线AC，BD相交于点O，AE垂直平分OB于点E，则AD的长为____．

下列城市化进程图分别表示的国家是(     )