如图，直径为10的⊙A经过点C(0，5)和点0(0，0)，B是y轴右侧⊙A优弧上一点，则∠OBC的余弦值为(    )

河水 $\underset{}{\overset{}{\to }}$  A(明矾) $\underset{}{\overset{}{\to }}$  B(沉淀) $\underset{}{\overset{}{\to }}$ C(过滤) $\underset{}{\overset{}{\to }}$ D(漂白粉 $\underset{}{\overset{}{\to }}$ 净水

    I really love football. I' m a member (成员) of our school football team (队) and I play four times a week. I also like swimming and I go swimming after school. I don't like basketball.

                                                                        Jack

    My favourite sport is basketball. I also like table tennis, but I don't play it at school. I go to a club (俱乐部) with my friends. I' m not very good at football.

                                                                        Anna

    Bicycle riding (骑自行车) is my fav0urite sport. I go to school by bicycle. I also like travelling (旅游) by bicycle and I-do it with my father. It's very interesting. I don't like football or" basketball.

                                                                     David

    I like football. It's really interesting. My two brothers are in our school football team and they help me. I don't like playing it with my friends.
                                                                    John.

关于x的二次三项式x²+7x-m可分解为(x+3)(x-n)，则m、n的值为（   ）

增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。

删除：把多余的词用斜线（＼）划掉。

修改：在错的词下画一横线，并在该词下面写出修改后的词。

注意：1）每处错误及其修改均仅限一词。

2）只允许修改10处，多者（从第11处起）不计分。

    I once bought the beautiful bracelet from a store and felt excited when I tried it on. Sadly, I was soon disappointed at that my naughty kids broke it. But instead of just feel sad, I chose to repair it myself.

    To my greatly surprise, it didn't take a long time to do it. As time went by, I found that I was not happy with just repairing my breaking bracelets. I started making new bracelets out the materials from my old one. Later on, I begin to design on my own.

    Then I made my first deal. Back in 2013, I posted my bracelets on WeChat for the first time and several friends said that they wanted it. That was just the start. With many materials at hand, I made my designs into real.