某科研小组以难溶性钾长石（K₂O•Al₂O₃•6SiO₂）为原料，提取Al₂O₃、K₂CO₃等物质，工艺流程如下：

阅读下面短文，从短文后所给的A、B、C、D四个选项中选出能填入相应空白处的最佳选项。

Dear Sally,

    How are you? I'm happy that you can do the things you 1 at home. I never have fun, because there are too many 2 in my family. My parents are strict. I have to 3 at six o'clock every morning. And I have to make my bed 4 before breakfast and then go to school. I can't play with my friends after school. I have to do 5homework. After dinner I have to take the dog for 6 walk in the park. I can't watch TV on school nights. I have to 7 the violin for an hour. I can't go to bed late. I have to be in bed 8 nine o'clock. On weekends I have to clean my room and 9the dishes. I also have to go to learn the violin on Sundays. I'm 10 tired. Can you help me?

Yours,

Lisa

下列行为属于亲近社会的行为是（    ）

①过马路时，看见盲人，上前搀扶

②在公共汽车上给老人让座

③看到有人在公共场所乱涂乱写、乱贴广告而无动于衷

④参加献爱心活动，为灾区人民捐款

已知反比例函数y= $\frac{k}{x}$ 的图象经过点A（1，﹣2），则k=____．