帮忙改一下小弟这篇托福综合写作作文~

帮忙改一下小弟这篇托福综合写作作文~
The author believes that the ''swamp gas'' hypothesis far out weighs the " outer object"explanation.However ,the lecture has a totally different idea on the topic made in the reading.
The first point the lecturer uses to cast doubt on the reading is that the absence of fragment on earth cannot support the idea that the explosion was not caused by an outer space object.The author is convinced that if the accident was caused by an asteroid,there must be a huge crater on the surface of the ground,yet no traces are found in the area.However,the speaker points out that after 90 years' of natural changes,the traces can be eliminated completedly.
In the second place,the reading made the point that the absence of huge craters has weakened the theory to some extend.To the contrary,the speaker states that the asteroid could explode before it reached the ground,so it is quite reasonable to find nothing after the explosion.
Lastly.the lecturer enhanced her standpoint by adding the fact that the whole process can involve a large area instead just one spot,which is not anticipated the the author.
In conclusion,the passagge completely refuses the reading.