Day 27

英文重現

Our first studies sought to determine whether the increase in serotonin observed in rats given a large injection of the amino acid tryptophan might also occur after rats ate meals that change tryptophan levels in the blood.

——GMAT OG 2015, Reading Comprehension, Passage 17

解析

“determine”后面的部分是由“whether”引導的賓語從句。該賓語從句的主語為“the increase in serotonin”，兩個過去分詞結構“observed in rats”和“given a large injection of the amino acid tryptophan”都是作后置定語，分別修飾“increase in serotonin”和“rats”；情態動詞“might”和動詞“occur”構成賓語從句的謂語，“after rats ate meals that change tryptophan levels in the blood”是“after”引導的時間狀語從句，該從句中的“that”引導的定語從句修飾“meals”。

詞義辨析

參考翻譯

我們起初的研究試圖確定：小白鼠被注射大量氨基酸色氨酸之后血清素上升（的情況）是否也會在小白鼠吃完能夠改變血液中色氨酸水平的食物之后發生。

實戰演練

Our first studies sought to determine whether the increase in serotonin observed in rats given a large injection of the amino acid tryptophan might also occur after rats ate meals that change tryptophan levels in the blood. We found that, immediately after the rats began to eat, parallel elevations occurred in blood tryptophan, brain tryptophan, and brain serotonin levels. These findings suggested that the production and release of serotonin in brain neurons were normally coupled with blood-tryptophan increases…

According to the passage, when the authors began their first studies, they were aware that

(A) they would eventually need to design experiments that involved feeding rats high concentrations of protein.

(B) tryptophan levels in the blood were difficult to monitor with accuracy.

(C) serotonin levels increased after rats were fed meals rich in tryptophan.

(D) there were many neuro transmitters whose production was dependent on metabolic processes elsewhere in the body.

(E) serotonin levels increased after rats were injected with a large amount of tryptophan.

答案：E

答案解析

根據“first studies”定位到原文“Our first studies sought to determine whether the increase in serotonin observed in rats given a large injection of the amino acid tryptophan might also occur after rats ate meals that change tryptophan levels in the blood”，為方便理解，可將原文句子簡化為“our first studies sought to determine whether A might also occur after...”，如此一來，我們便可以很容易知道A所代替的內容即為此次研究之前已經知道的信息，所以本題的答案就是A所代替的內容，即“increase in serotonin observed in rats given a large injection of the amino acid tryptophan”，那么就不難選出選項E“小白鼠被注射大量氨基酸色氨酸之后血清素上升”。

選項C“老鼠被喂食富含色氨酸的食物后血清素水平上升了”有迷惑性，錯在“喂食”，應該是“注射”。

其他選項意思分別為：

A.它們最終需要設計實驗，給小白鼠喂食高濃度的蛋白質。

B.血液中色氨酸水平很難被精確地監控。

D.有很多神經遞質的產生取決于身體其他地方的新陳代謝過程。