观察下列等式

1²=1= $\frac{1}{6}$ ×1×2×（2+1）

1²+2²= $\frac{1}{6}$ ×2×3×（4+1）

1²+2²+3²= $\frac{1}{6}$ ×3×4×（6+1）

1²+2²+3²+4²= $\frac{1}{6}$ ×4×5×（8+1）…

可以推测1²+2²+3²+…+n²=____．

实验室用密度为1.84g/cm3、质量分数为98%的浓硫酸和蒸馏水，配制500g 质量分数为20%的稀硫酸．需要用多少mL的量筒量取多少mL的浓硫酸？（　　）

Interviewer: Hi, Grandma Li. Welcome to our programme (节目).____

Grandma Li: Life was very different in China many years ago.

Interviewer:____

Grandma Li: We lived in a small house. We didn't have enough food.____

Interviewer: How about now?

Grandma Li:____We have got lots of food. There are lots of buses and cars. Life is convenient (方便的）now. I enjoy my life.

Interviewer:____Goodbye.

Grandma Li: Bye.

纯碱是造纸、玻璃、纺织、制革等行业的重要原料．