阅读材料
A huge marine mammal known as Steller's sea cow once lived in the waters around Bering Island off the coast of Siberia. It was described in 1741 by Georg W. Steller, a naturalist who was among the first Europeans to see one. In 1768 the animal became extinct. The reasons for the extinction are not clear. Here are three theories about the main cause of the extinction.
First, the sea cows may have been overhunted by groups of native Siberian people. If this theory is correct, then the sea cow population would have originally been quite large, but hundreds of years of too much hunting by the native people diminished the number of sea cows. Sea cows were a good source of food in a harsh environment, so overhunting by native people could have been the main cause of extinction.
Second, the sea cow population may have become extinct because of ecosystem disturbances that caused a decline in their main source of food, kelp (a type of sea plant). Kelp populations respond negatively to a number of ecological changes. It is possible that ecological changes near Bering Island some time before 1768 caused a decrease of the kelp that the sea cows depended on.
Third, the main cause of extinction of the sea cows could have been European fur traders who came to the island after 1741. It is recorded that the fur traders caught the last sea cow in 1768. It thus seems reasonable to believe that hunting by European fur traders, who possessed weapons that allowed them to quickly kill a large number of the animals, was the main cause of the sea cow's extinction.
The reading and the lecture are both related to the extinction of Stella's sea cows that once lived in the waters around Bering island off the coast of Siberia. In the reading, the author proposes three possible causes for its extinction, however, the lecturer challenges each one with its flaws.
In the first theory, it is suggested that the sea cows may be hunted by the natives of the Bering island for food. Yet, the lecturer contends that the sea cows are massive marine animals that are nine meters long and weighs over 10 tons. Thus, even if the natives were to hunt them for food, they would not hunt a large amount of them since the scale of the native villages were rather small at that time. In the result, it seems impossible for the inhabitants to kill them to the extent that cause their extinction.
As the next theory indicates that the main food source diminished due to ecosystem changes, the author contends that it may be the reason why the sea cows go extinct. On the contrary, the lecturer believes that such kind of ecosystem changes must have impacted other species, while there was no evidence for that. For example, the fisher in that area didn't report any unusual decrease in the number of whales. Thus, without further evidence, it is hard to conclude that the sea cow died out because of declined food resources.
Finally, the third theory might seem like an explanation since the extinction happens right after the European fur traders' arrival. However, the lecturer proposes the other interpretation. He claims that by the time they came to the island, the group of the sea cows were quite small compared to their largest scale which was hundreds of years before. Consequently, some other events must have happened before 1941 that caused the ongoing decrease of the see cows population. The third possible cause is thus rejected by the lecturer.
In conclusion, there is a large division between the opinions of the author and of the lecturer. The lecturer refutes each of the points mentioned by the author.
Grammar and spelling errors:
Line 5, column 352, Rule ID: EN_CONTRACTION_SPELLING
Message: Possible spelling mistake found
Suggestion: didn't
...t. For example, the fisher in that area didnt report any unusual decrease in the numb...
^^^^^
Line 7, column 116, Rule ID: POSSESIVE_APOSTROPHE[2]
Message: Possible typo: apostrophe is missing. Did you mean 'traders'' or 'trader's'?
Suggestion: traders'; trader's
...on happens right after the European fur traders arrival. However, the lecturer proposes...
^^^^^^^
Transition Words or Phrases used:
consequently, finally, first, however, if, may, so, third, thus, while, for example, in conclusion, kind of, on the contrary
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 14.0 10.4613686534 134% => OK
Auxiliary verbs: 6.0 5.04856512141 119% => OK
Conjunction : 3.0 7.30242825607 41% => More conjunction wanted.
Relative clauses : 15.0 12.0772626932 124% => OK
Pronoun: 28.0 22.412803532 125% => Less pronouns wanted
Preposition: 48.0 30.3222958057 158% => OK
Nominalization: 9.0 5.01324503311 180% => OK
Performance on vocabulary words:
No of characters: 1700.0 1373.03311258 124% => OK
No of words: 353.0 270.72406181 130% => OK
Chars per words: 4.81586402266 5.08290768461 95% => OK
Fourth root words length: 4.33454660006 4.04702891845 107% => OK
Word Length SD: 2.38171361984 2.5805825403 92% => OK
Unique words: 195.0 145.348785872 134% => OK
Unique words percentage: 0.552407932011 0.540411800872 102% => OK
syllable_count: 519.3 419.366225166 124% => OK
avg_syllables_per_word: 1.5 1.55342163355 97% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 5.0 3.25607064018 154% => OK
Article: 12.0 8.23620309051 146% => OK
Subordination: 3.0 1.25165562914 240% => Less adverbial clause wanted.
Conjunction: 0.0 1.51434878587 0% => OK
Preposition: 6.0 2.5761589404 233% => Less preposition wanted as sentence beginnings.
Performance on sentences:
How many sentences: 17.0 13.0662251656 130% => OK
Sentence length: 20.0 21.2450331126 94% => OK
Sentence length SD: 35.1889609932 49.2860985944 71% => OK
Chars per sentence: 100.0 110.228320801 91% => OK
Words per sentence: 20.7647058824 21.698381199 96% => OK
Discourse Markers: 7.29411764706 7.06452816374 103% => OK
Paragraphs: 5.0 4.09492273731 122% => OK
Language errors: 2.0 4.19205298013 48% => OK
Sentences with positive sentiment : 3.0 4.33554083885 69% => OK
Sentences with negative sentiment : 4.0 4.45695364238 90% => OK
Sentences with neutral sentiment: 10.0 4.27373068433 234% => Less facts, knowledge or examples wanted.
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.178419665166 0.272083759551 66% => OK
Sentence topic coherence: 0.0534585825571 0.0996497079465 54% => OK
Sentence topic coherence SD: 0.079280658342 0.0662205650399 120% => OK
Paragraph topic coherence: 0.0933636381969 0.162205337803 58% => OK
Paragraph topic coherence SD: 0.0681229374995 0.0443174109184 154% => OK
Essay readability:
automated_readability_index: 11.7 13.3589403974 88% => Automated_readability_index is low.
flesch_reading_ease: 59.64 53.8541721854 111% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 9.9 11.0289183223 90% => OK
coleman_liau_index: 10.68 12.2367328918 87% => OK
dale_chall_readability_score: 8.21 8.42419426049 97% => OK
difficult_words: 80.0 63.6247240618 126% => OK
linsear_write_formula: 9.0 10.7273730684 84% => OK
gunning_fog: 10.0 10.498013245 95% => OK
text_standard: 10.0 11.2008830022 89% => OK
What are above readability scores?
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Write the essay in 20 minutes.
Rates: 60.0 out of 100
Scores by essay e-grader: 18.0 Out of 30
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Note: the e-grader does NOT examine the meaning of words and ideas. VIP users will receive further evaluations by advanced module of e-grader and human graders.