make questions, then work with a friend and ask and answer
1.walked/Mars /on/people /have?
2.the /has/changed/climate?
3.we/environment/the/have/ protected?
4.pollution/trees/has/a lot of/destroyed?
5.stayed/the/has/same/world/the ?

2) Yes, it has.

1) Have people walked on Mars? - No, they haven't.2)Has the climate changed? - Yes, he has.3) Have we protected the enviroment? Yes, we have.4) Has pollution destroyed a lot of trees? - Yes, it has.5) Has the world stayed the same? - No, it hasn't.