Starting in the 1960s and continuing until the 1980s, sailors in Russian submarines patrolling the North Alantic and Arctic Ocean would occasionally hear strange sounds. These underwater noises reminded the submarine crews of frog croaks, so they called the sounds “quackers” (from the Russian word for frog sounds). The sources of the sound seemed to be moving with great speed and agility; however, the submarines’ sonar (a method of detecting objects underwater) was unable to detect any solid moving objects in the area. There are several theories about what might have caused the odd sounds.
The first theory suggests that the strange noises were actually the calls of male and female ocra whales during a courtship ritual. Orca whales are known to inhabit the areas where the submarines were picking up the bizarre noises. Orcas have been studied extensively, and the sounds they make when trying to attract a male are similar to those that the submarines were detecting.
A second idea is that the sounds were caused by giant squid. Giant squids are gaint marine invertebrates that live deep in the ocean and prey on large fish. They are difficult to detect by sonar because they have soft bodies with no skeleton. Not much is known about giant squid behavior, but their complex brains suggest they are intelligent animals. It is possible they have the ability to emit sound, and perhaps they approached the submarines out of curiosity.
A third theory suggests the Russian submarines were picking up stray sounds from some military technology, like another country’s submarines that were secretly patrolling the area. Perhaps the foreign submarines did not register on sonar because they were using a kind of technology specifically designed to make them undetectable by sonar. The strange froglike sounds may have been emitted by the foreign submarines unintentionally.
The reading passage explores the possibility of the existence of an ancient weapon called 'burning mirror' and concludes that this kind of weapon is just a myth. However, the professor inthe lecture does not concur with it and holds the view that burning mirror is effective and practical enough to be built. And he uses 3 points to support hisopinion.
Initially, the professor rejects the claimin the reading passage that ancient Greeks did not equip advanced technology to posses burning mirror. According to the passage, such device requires to be several meters wide and have an exact parabolic curvature, which cannot be realized in ancient times. Differing from the statement, the professor contends thatburning mirror can exist with the help of a special method. She cites an experiment to illustrate this idea. Instead of making a single large sheet of copper, which is impossible in ancient times, ancient Greeks can arrange dozensof individual copper sheets into a large burning mirror. Besides, Greek mathematicians are well-versed to have the knowledge of the property of parabolas which directs the construction of those merged copper mirrors.
Moreover, the author of the reading passage cites an experiment on wood to aver that it is time-consuming to set the shipson fire during the war. Also, those ships must be still, which is unlikely to realize. The professor admits that to set wooden objects on fire truly need a considerable amount of time. Nevertheless, there is another material to make burning mirror practical. This waterproof and sticky material, which is used to seal the gaps between the wooden parts of ships, is called pitch. They can catch fire in just a few seconds and quickly spread fire to woods. Therefore, even if ships are moving, fire still can spread within a fleeting time.
Finally, the professor casts doubt on theview of the reading passage that flaming arrow can substitute burning mirror because both are equally effective at the same distance. In such case, burning mirror has no reason to exist. The professor argues that flaming arrow is not flawless. Ancient Romes are quite familiar with this weapon and therefore get prepared to defend the fire. By contrast, the rays from burning mirror are invisible, which certainly surprise Greek's enemy. For this reason, burning mirror is effective.
Discourse Markers used:
['also', 'besides', 'finally', 'however', 'if', 'moreover', 'nevertheless', 'second', 'so', 'still', 'therefore', 'well', 'kind of']
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance in Part of Speech:
Nouns: 0.247706422018 0.261695866417 95% => OK
Verbs: 0.188073394495 0.158904122519 118% => OK
Adjectives: 0.0871559633028 0.0723426182421 120% => OK
Adverbs: 0.0550458715596 0.0435111971325 127% => OK
Pronouns: 0.0114678899083 0.0277247811725 41% => OK
Prepositions: 0.0917431192661 0.128828473217 71% => OK
Participles: 0.0550458715596 0.0370669169778 149% => OK
Conjunctions: 2.62386339919 2.5805825403 102% => OK
Infinitives: 0.0366972477064 0.0208969081088 176% => OK
Particles: 0.0 0.00154638098197 0% => OK
Determiners: 0.112385321101 0.128158765124 88% => OK
Modal_auxiliary: 0.0160550458716 0.0158828679856 101% => OK
WH_determiners: 0.0160550458716 0.0114777025283 140% => OK
Vocabulary words and sentences:
No of characters: 2367.0 1645.83664459 144% => OK
No of words: 382.0 271.125827815 141% => OK
Chars per words: 6.19633507853 6.08160592843 102% => OK
Fourth root words length: 4.42095241839 4.04852973271 109% => OK
words length more than 5 chars: 0.434554973822 0.374372842146 116% => OK
words length more than 6 chars: 0.303664921466 0.287516216867 106% => OK
words length more than 7 chars: 0.178010471204 0.187439937562 95% => OK
words length more than 8 chars: 0.128272251309 0.113142543107 113% => OK
Word Length SD: 2.62386339919 2.5805825403 102% => OK
Unique words: 212.0 145.348785872 146% => OK
Unique words percentage: 0.55497382199 0.539623497131 103% => OK
Word variations: 62.9564396869 53.8517498576 117% => OK
How many sentences: 22.0 13.0529801325 169% => OK
Sentence length: 17.3636363636 21.7502111507 80% => OK
Sentence length SD: 45.1431378236 49.3711431718 91% => OK
Chars per sentence: 107.590909091 132.220823453 81% => OK
Words per sentence: 17.3636363636 21.7502111507 80% => OK
Discourse Markers: 0.590909090909 0.878197800319 67% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 0.0 3.39072847682 0% => OK
Readability: 47.7301285102 50.5018328374 95% => OK
Elegance: 1.54954954955 1.90840788429 81% => OK
Coherence and Cohesion:
Essay topic to essay body coherence: 0.291242250164 0.549887131256 53% => OK
Sentence sentence coherence: 0.0740481824557 0.142949733639 52% => OK
Sentence sentence coherence SD: 0.0643951591245 0.0787303798458 82% => OK
Sentence paragraph coherence: 0.463549239638 0.631733273073 73% => OK
Sentence paragraph coherence SD: 0.141572515501 0.139662658121 101% => OK
Sentence topic coherence: 0.109985363325 0.266732575781 41% => OK
Sentence topic coherence SD: 0.0831965567709 0.103435571967 80% => OK
Paragraph paragraph coherence: 0.416391447917 0.414875509568 100% => OK
Paragraph paragraph coherence SD: 0.0341976521327 0.0530846634433 64% => OK
Paragraph topic coherence: 0.228900565204 0.40443939384 57% => OK
Paragraph topic coherence SD: 0.0343357072187 0.0528353158467 65% => The ideas may be duplicated in paragraphs.
Task Achievement:
Sentences with positive sentiment : 7.0 4.33554083885 161% => OK
Sentences with negative sentiment : 8.0 4.45695364238 179% => OK
Sentences with neutral sentiment: 7.0 4.26048565121 164% => OK
Positive topic words: 5.0 3.49668874172 143% => OK
Negative topic words: 5.0 3.62251655629 138% => OK
Neutral topic words: 3.0 3.1766004415 94% => OK
Total topic words: 13.0 10.2958057395 126% => OK
What are sentences with positive/Negative/neutral sentiment?
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Less content wanted. Write the essay in 30 minutes.
Rates: 86.6666666667 out of 100
Scores by essay e-grader: 26.0 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.