设椭圆C： $\frac{x^2}{a^2}$ + $\frac{y^2}{b^2}$ =1（a＞b＞0）的左、右焦点分别为F₁、F₂，上顶点为A，过A与AF₂垂直的直线交x轴负半轴于Q点，且F₁恰好是线段QF₂的中点．

在豆浆中加入盐卤或石膏，能制成豆腐，这是利用了大豆中蛋白质的什么性质？____ ．蛋白质受热、遇到硝酸、重金属盐溶液、甲醛等物质，会引起分子结构发生变化，导致蛋白质丧失原有的生理功能，称为蛋白质的变性，这里的变性应该是____ （填物理变化或化学变化），从上述的内容中你受到哪些启发？____ ．

人误服重金属盐中毒后．为了减轻毒性．可服用下列物质中的____ 

A．牛奶       B．食盐水       C．鸡蛋清       D．肥皂水．

我国优越的地理位置是（    ）

①北半球    ②南半球   ③东半球   ④西半球    ⑤亚洲东部       ⑥太平洋西岸

⑦大部分位于北温带，南部部分地区位于热带，没有寒带            ⑧太平洋东岸   ⑨中纬度．

阅读短文，下列问题

 B

    The plane took off. A passenger needed a cup of water to take his medicine. An air hostess(空姐) told him that she would bring him the water soon. But the air hostess was so busy that she forgot to bring him the water. As a result, the passenger couldn't take his medicine on time. About half an hour later, she hurried over to him with a cup of water, but he refused it.

    In the following hours, each time she passed by the passenger, she would ask him with a smile whether he needed help or not. But the passenger never paid notice to her.

    When it was time to get off the plane, the passenger asked her to hand him the passengers' booklet(留言簿), she was very sad. She thought that he would write down bad words in it, but with a smile she handed it to him.

    Off the plane, she opened the booklet and then smiled. The passenger put it, “In the past few hours, you have asked me whether I needed help or not for twelve times in all. How can I refuse your twelve faithful(真诚的) smiles?”