3.平行，前面的是书那后面的也必须是书，排除acd
且前面是Jean Toomer's Cane，(b) is not as parallel as (e), either. since the original says "jean toomer's cane", the others should also have the form "X's Y", not "Y by X".
1.单复数问题：novels ever written by Black Americans/a Black American都可以。
借用Ron大神的例子，birds have a four-chambered heart和birds have four-chambered hearts,这两个都可以，且前者更好。套用到本题上就是，the three best novels这一类书都有一个特点，即由一个黑人作者所写。
the problem, though, is that "the intentional discarding of lens caps, packing material , fuel tanks and payload covers" IS the "littering".
so, sentences D and E are not logical.
'because of' must be followed by SOMETHING ELSE that is actually the cause of something.
'with' should be followed by a component or part of the previous observation.
In #C there's no NOUN that serves as the focus of the modifier 'resulting from...' (an adjective-type modifier). It's intended to modify the general idea that the orbits have become littered, but there's no NOUN that signifies the littering.
需要对文章的层次有深度的理解才能做对这些难度问题。
文章层层递进， 先是讲tooth pattern can help determine animal's diet. 然后讲 it has certain limitation when it comes to insect eating as only hard insect will cause tooth abrasion for baboon. 但是提到的cause indifferent tooth pattern的食物其实只有insect，所以由于物种地域分隔导致他们吃不同的食物还是有可能导致different tooth pattern.
A. 会不精确地反映baboon吃的软体虫比硬体虫多 - 显然错误，因为反应不出来。
B. 会反映虫子是baboon食谱组成的重要部分 - 看不出来的，错误。
C. 会揭露baboon的 tooth pattern没有什么特别的不同 - 这个是强干扰选项。它扩大了limitation的范围。无法区分的仅限于虫子（可能也会有其他的食物种类但是文章中没提），而其他的食物完全可能导致baboon的tooth pattern不同于彼此。
D. 正确选项，完全对应文中的意思把食物种类限定在虫子。
E. 会揭示baboon在不同地区吃不同的虫子 - 错误，看不出来的。
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单数的理解：这三本书的每一本都是由一位黑人作家所写。