Invasive species cause most of the worst problems in local ecosystems. The presence of a new species, particularly one at the top of the food chain, can destroy an ecosystem and cause numerous species to become extinct. One species that is causing numerou

Essay topics: Invasive species cause most of the worst problems in local ecosystems. The presence of a new species, particularly one at the top of the food chain, can destroy an ecosystem and cause numerous species to become extinct. One species that is causing numerous problems in America’s waterway is the aquatic zebra mussel.

Native to Russia, the zebra mussel has recently invaded the Great Lakes and many other American lakes and rivers. The mussels attach themselves to the bottoms of boats, a convenient method that lets them travel easily. They also often attach themselves to water pipes. This action results in clogged pipes, some of which are used to bring drinking water to cities. The blocked pipes cost the cities huge amounts of money to unblock. Also, zebra mussels reproduced so rapidly that they often smother the spawning grounds of various fish and other mussels, thereby prohibiting their growth.

Additionally, zebra mussels in North America have very few natural enemies, meaning that it is diffcult to eliminate them once they are established in a river or lake. Likewise, scientists have yet to discover an environmentally-safe way to kill zebra mussels. These two facts help contribute to the extremely rapid expansion of the zebra mussels. Should this expansion not be stopped, zebra mussels will soon be causing problems in virtually all of the country’s waterways.

Essay topics in audio: 
Minh Giang Nguyen's picture

The main issue discussed in the reading passage is zebra mussels, an invasive species, and its damage in local ecosystems. In the lecturer, the professor provides several solutions for this problem.

Firstly, according to the reading passage, that zebra mussels attach themselves to water pipes block pipes, some of which are used to bring drinking water to cites. The professor discusses decontaminate boats in American lakes and rivers as a step to address this problem. She mentions this because zebra mussels stick themselves to the bottoms of ships to travel. Thus, the ships should be clean by sea water to kill zebra mussel. Furthermore, the mussels can survive out of water several days, so other ship parts out of water like anchor chains should be also decontaminated. Overall, this solution is able decrease the number of zebra mussel and opening the pipes.

Secondly, the another problem is scientists are unable to discover safe method to kill zebra mussel because it has very few natural enemies. The professor indicates that there are some kind of species like duck, bird or fish which eat zebra mussel. However, the number of these species is not enough to make impact on the number of zebra mussel. Therefore, the lecturer suggests that the scientists should increase the number of these predators which hunt the mussel for food. In conclusion, this solution is an environmentally-safe method to eliminate zebra mussel.

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Average: 8 (1 vote)
This essay topic by other users:
Post date Users Rates More about the essay
1 year 3 months ago dshah6611 71 Read full essay
3 years 2 months ago Minh Giang Nguyen 86 Read full essay
3 years 2 months ago Minh Giang Nguyen 83 Read full essay
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Comments

Grammar and spelling errors:
Line 5, column 186, Rule ID: THERE_RE_MANY[3]
Message: Possible agreement error. Did you mean 'kinds'?
Suggestion: kinds
...professor indicates that there are some kind of species like duck, bird or fish whic...
^^^^

Discourse Markers used:
['also', 'first', 'firstly', 'furthermore', 'however', 'second', 'secondly', 'so', 'therefore', 'thus', 'in conclusion', 'kind of']

Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments

Performance in Part of Speech:
Nouns: 0.290076335878 0.261695866417 111% => OK
Verbs: 0.141221374046 0.158904122519 89% => OK
Adjectives: 0.0839694656489 0.0723426182421 116% => OK
Adverbs: 0.0343511450382 0.0435111971325 79% => OK
Pronouns: 0.0190839694656 0.0277247811725 69% => OK
Prepositions: 0.110687022901 0.128828473217 86% => OK
Participles: 0.0229007633588 0.0370669169778 62% => OK
Conjunctions: 2.68812930409 2.5805825403 104% => OK
Infinitives: 0.0458015267176 0.0208969081088 219% => Less infinitives wanted.
Particles: 0.0 0.00154638098197 0% => OK
Determiners: 0.12213740458 0.128158765124 95% => OK
Modal_auxiliary: 0.0152671755725 0.0158828679856 96% => OK
WH_determiners: 0.0114503816794 0.0114777025283 100% => OK

Vocabulary words and sentences:
No of characters: 1445.0 1645.83664459 88% => OK
No of words: 234.0 271.125827815 86% => More content wanted.
Chars per words: 6.17521367521 6.08160592843 102% => OK
Fourth root words length: 3.91114542567 4.04852973271 97% => OK
words length more than 5 chars: 0.388888888889 0.374372842146 104% => OK
words length more than 6 chars: 0.290598290598 0.287516216867 101% => OK
words length more than 7 chars: 0.188034188034 0.187439937562 100% => OK
words length more than 8 chars: 0.0982905982906 0.113142543107 87% => OK
Word Length SD: 2.68812930409 2.5805825403 104% => OK
Unique words: 133.0 145.348785872 92% => OK
Unique words percentage: 0.568376068376 0.539623497131 105% => OK
Word variations: 55.3589819163 53.8517498576 103% => OK
How many sentences: 13.0 13.0529801325 100% => OK
Sentence length: 18.0 21.7502111507 83% => OK
Sentence length SD: 27.9492354692 49.3711431718 57% => OK
Chars per sentence: 111.153846154 132.220823453 84% => OK
Words per sentence: 18.0 21.7502111507 83% => OK
Discourse Markers: 0.923076923077 0.878197800319 105% => OK
Paragraphs: 3.0 4.09492273731 73% => OK
Language errors: 1.0 3.39072847682 29% => OK
Readability: 47.0598290598 50.5018328374 93% => OK
Elegance: 2.17647058824 1.90840788429 114% => OK

Coherence and Cohesion:
Essay topic to essay body coherence: 0.388749509475 0.549887131256 71% => OK
Sentence sentence coherence: 0.117486224104 0.142949733639 82% => OK
Sentence sentence coherence SD: 0.0740796727492 0.0787303798458 94% => OK
Sentence paragraph coherence: 0.556275929661 0.631733273073 88% => OK
Sentence paragraph coherence SD: 0.120051778975 0.139662658121 86% => OK
Sentence topic coherence: 0.17787921493 0.266732575781 67% => OK
Sentence topic coherence SD: 0.0838590152204 0.103435571967 81% => OK
Paragraph paragraph coherence: 0.375698079178 0.414875509568 91% => OK
Paragraph paragraph coherence SD: 0.0946395764556 0.0530846634433 178% => OK
Paragraph topic coherence: 0.308132580281 0.40443939384 76% => OK
Paragraph topic coherence SD: 0.0412759717238 0.0528353158467 78% => The ideas may be duplicated in paragraphs.

Task Achievement:
Sentences with positive sentiment : 6.0 4.33554083885 138% => OK
Sentences with negative sentiment : 6.0 4.45695364238 135% => OK
Sentences with neutral sentiment: 1.0 4.26048565121 23% => More neutral sentences wanted.
Positive topic words: 6.0 3.49668874172 172% => OK
Negative topic words: 6.0 3.62251655629 166% => OK
Neutral topic words: 1.0 3.1766004415 31% => OK
Total topic words: 13.0 10.2958057395 126% => OK
What are sentences with positive/Negative/neutral sentiment?

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Not in a correct format.

The correct pattern:
para 1: introduction
para 2: doubt 1
para 3: doubt 2
para 4: doubt 3

Less contents wanted from the reading passages(25%) but more content wanted from the lecture (75%).

Don't need a conclusion paragraph.

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http://www.testbig.com/users/toeflwritingmaster

Rates: 80.0 out of 100
Scores by essay e-grader: 24.0 Out of 30
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Note: This is not the final score. 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.

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