Toefl integrated essay：Were there life-form on Mars？

This is my tofel integrated essay
Theme：summarize the points made in the lecture you just heard，explaining how they cast doubt on points made in the reading。
Thanks a lot ~~~

The reading passage offers three evidences that life-form has existed on Mars 。The lecture completely refutes the passage.
First of all ，the lecture says ，observeing the fossil with the aid of microscopes may change its real characteristic feature ，which make it is similar to the fossils which have been found on earth 。However,this departs from the reading passage,which contends that tube-like fossil can testify that some living things have been there 。

Secondly，the lecture belives that the special chemical compounds found on Mars maybe form by volcanic explosion on earth or come from other non life form activities。Therefore, this directly contradicts what the passage indicates.

Thirdly，oppseing the reading which points grains and bactria have been found on Mars，the lecture demonstrates that the magnetic field on Mars are not as strong the magnetic field on earth，the bacteria are too week to follow the meteorites and the grains were useless.

The reading passage offers three evidences that life-form has existed on Mars 。The lecture completely refutes the passage.
First of all ，the lecture says ，observeing the fossil with the aid of microscopes may change its real characteristic features ，which makes it is similar to the fossils whichare found on earth 。However,this departs from the reading passage,it sounds reli weird "this departs from the reading" which contends that tube-like fossil can testify that some living things have been there 。

Secondly，the lecture belives that the special chemical compounds found on Mars may be formed by volcanic explosions on earth or come from other non life form activitiesi dont get what ur trying to say 。Therefore, this directly contradicts what the passage indicates.

Thirdly，opposing the reading opposing the reading doesnt make sense

which points grains and bactria have been found on Mars，the lecture demonstrates that the magnetic field on Mars is not as strong the magnetic field on Earth ，the bacteria are too week to follow the meteorites and the grains were useless. this is a run on sentence

ur essay is somewhat confusing and you need to re-read wat u write, esp the grammer you use.

Thinks for your help.Sometimes I try to use different sentences to express the same meaning,but I always mess up .For example,I used "this departs from the reading" instead of "The lecture completely refutes the passage".

Good example!
These have slightly different meanings, though!! If you say it completely refutes the passage, it sounds like it completely disproves the passage. However, if you say the lecture departs from the reading, it sounds like the lecture only contradicts the reading.

The reading passage offers three evidences that life-forms have existed on Mars。The lecture completely refutes the passage.

Secondly，the lecturer believes that the ... --- I changed it to lecturer, because a lecturer is a person. A person can believe, but a lecture cannot believe.

special chemical compounds found on Mars, maybe formed by volcanic explosions on ...

Thirdly，while the reading points to grains and bacteria that have been found on Mars，the lecture ...

:-)