To a growing number of US students in China, study in the ancient country is no longer just a cultural experience it has become an important part of their future professional careers.

    Sam Gor, a 26-year-old student from Santa Clara, a county near San Francisco, said the purpose of his studies in Beijing was to help him find a good job when he goes back to the United States. "Culture matters," he said. "But more importantly, to learn Chinese and get a better understanding of the country may help me professionally." As a new student at Beijing Language and Culture University (BLCU), Gor hopes to find a job in Santa Clara's local government when he goes back home in one year. "I need to learn Chinese if I want the job, as we have a large Chinese community there."

    Gor is not alone in his thinking. While the number of US students in China has grown from less than 100 in the early 1980s to more than 10,000 for the time being. Many of them are here to boost(提高) a professional skill as much as to enjoy a new culture.

    “In the past, foreign students came to China simply for our culture,” said Xu Quihan, director of BLCU's foreign students' office. “But because of China's rapid economic and social development, being able to speak Chinese has become a useful tool to a student's future job”

    There are more US students who choose to stay in the country instead of going back after graduation. Stephanie Schubmehlo, a 23-year-old from Rochester, New York State, said she would like to stay in Beijing after graduation. “I love the city, and I can earn myself a living here if I can speak good Chinese,” she said, adding that some of the US students she knows shared the same idea.

锌和铝都是活泼金属，其氢氧化物既能溶于强酸，又能溶于强碱。但是氢氧化铝不溶于氨水，而氢氧化锌能溶于氨水，生成Zn(NH₃)₄²⁺。

回答下列问题：

父亲的自行车

    ①有人说，十岁的小孩子崇拜父亲，二十岁的青年人鄙视父亲，四十岁的中年人怜悯父亲。然而，对我来主，这个世界上父亲是惟一值得一辈子崇拜的人。

    ②父亲是建筑师，工地上所有的工作都怕他，沙子与水泥的比例有一点差错也会招来父亲的痛斥。然而，父亲在家里永远是慈爱的，他的好脾气甚至超过了母亲。在县城里，父亲的自行车众人皆知，每天早晚，他风雨无阻地骑着吱吱嘎嘎的破车接送我和弟弟上下学。那时，我和弟弟总手拉着手跑出校门，一眼就看见站在破自行车旁，穿着旧蓝色中山服焦急地张望着的父亲。一路上，两个小家伙叽叽喳喳地说个不停，而父亲一直能一心两用，一边乐滋滋地听着，一边小心翼翼地避过路上数不清的坑坑洼洼。等到我上了初中，父亲的车上便少了一个孩子；等到弟弟也上了初中，父亲便省去了一天两趟的奔波。可父亲似乎有些怅然若失，儿子毕竟一天天长大了。

    ③收到大学录取通知书的那天，我兴奋得睡不着觉。半夜里听见客厅里有动静，起床看，原来是父亲，他正在台灯下翻看一本发黄的相片簿。看见我，父亲微微一笑，指着一张打篮球的照片说：“这是我刚上大学时照的！”照片上，父亲生龙活虎，眼睛炯炯有神，好一个英俊的小伙子！此刻，站在父亲身后的我却蓦然发现，父亲的脑后已有好些白发了。父亲一出世便失去了自己的父亲，惨痛的经历使他深刻地意识到父亲对儿子的重要性。因此，在生活里，除了工作便是妻儿，他不吸烟不喝酒，不钓鱼不养花，在办公室与家的两点一线间，生活得有滋有味。辅导儿子的学习是他最大的乐趣，每天的家庭作业父亲都要一道道地检查，认认真真地签上家长意见，每次家长会上他都被老师称赞为“最称职的家长”。母亲还告诉我一件往事：我刚一岁的时候，一次急病差点夺去了我的小命。远在千里之外矿区工作的父亲把已经转危为安的我抱在怀里，几滴泪水落到我的脸上，我哇哇地哭了。“那些山路，全是悬崖绝壁，想起来也有些后怕。”许多年后父亲这样淡淡地提了一句。

    ④父亲是个不善于表达感情的人，与父亲在一起，沉默的时候居多，我却能感觉出自己那与父亲息息相通的心跳。离家后收到父亲的第一封信，信里有一句似乎很伤感话：“还记那辆破自行车吗？你走了以后，我到后院杂物堆里去找，却锈成一堆废铁了。”我想了许久，在一个阳光灿烂的早晨给父亲回信：“爸，别担心，那辆车每天晚上都在我的梦里出现呢。我坐在后面，弟弟坐在前面，您把车轮蹬得飞快……”

请阅读下列材料：若两个正实数a₁，a₂满足a₁²＋a₂²＝1，那么a₁＋a₂≤ $\sqrt{2}$ .

证明：构造函数f(x)＝(x－a₁)²＋(x－a₂)²＝2x²－2(a₁＋a₂)x＋1，因为对一切实数x，恒有f(x)≥0，所以Δ≤0，从而得4(a₁＋a₂)²－8≤0，所以a₁＋a₂≤ $\sqrt{2}$ .

根据上述证明方法，若n个正实数满足a₁²＋a₂²＋…＋a_n²＝1时，你能得到的结论为____．