1.How much time do you spend playing video games on weekends?                                           2. Which family owns the largest field for planing crops in the rural area?

1. I enjoy going to the park for a picnic for it allows me to relax in nature.                                                    2. We should go to this village in order to explore traditional ways of life.                                                     3.If we throw trash on the ground, the environment will gets dirty.

1.There are too many cars in some cities, and this causes air pollution.          2.She is crazy about taking photographs of beautiful landscapes and scenery.                      3.The river water is dirty enough to pose threat to aquatic life.

1.Avoid touching hot surfaces as they can burn you.                                    2.Are bicycles a popular mode of transport in the countryside?

a,x^2+25-10x=x^2-10x+25=(x-5)^2=(x-5)*(x-5).                                   b,-8y^3+x^3=(-2y)^3+x^3=(-2y+x)*[(-2y)^2-(-2y)*x+x^2]=(-2y+x)*[(-2y)^2+2y*x+x^2]=(-2y+x)*(4y^2+2xy+x^2)

 a,(2x+1)^2=(2x)^2+2*2x*1+1^2=4x^2+4x+1            b,(a-b/2)^3=a^3-3*a^2*b/2+3*a*(b/2)^2-(b/2)^3=a^3-3*a^2*b/2+3a*b^2/4-b^3/8