Saving the World

A student is talking to her teacher.
(S=student; T=teacher)
S : I hear that scientists are planning to study asteroids and meteors, right?
T : Yes. They want to determine whether Earth is in danger of being struck by such a rock.
S : What if they discover that a big one is coming straight for us?
T : In that case, there are two things they can do. They can launch rockets to push the rock off its course.
S : So that it will miss Earth, right?
T : Right. And if that fails, we can try destroying the rock with nuclear missiles.
S : Wow! I never thought that nuclear weapons could save the world instead of ending it!

学生:我听说科学家正计划研究小行星和陨石, 对不对?
老师:那样的话, 他们能做的有两件事。他们可以发射火箭将石头推离轨道。
学生:这样的话石头便撞不着地球了, 对不对?
老师:对。这个方法不成功的话, 我们还可以尝试用核子导弹来摧毁石块。