Day 27

英文重现

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”引导的宾语从句。该宾语从句的主语为“the increase in serotonin”，两个过去分词结构“observed in rats”和“given a large injection of the amino acid tryptophan”都是作后置定语，分别修饰“increase in serotonin”和“rats”；情态动词“might”和动词“occur”构成宾语从句的谓语，“after rats ate meals that change tryptophan levels in the blood”是“after”引导的时间状语从句，该从句中的“that”引导的定语从句修饰“meals”。

词义辨析

参考翻译

我们起初的研究试图确定：小白鼠被注射大量氨基酸色氨酸之后血清素上升（的情况）是否也会在小白鼠吃完能够改变血液中色氨酸水平的食物之后发生。

实战演练

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

根据“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”，为方便理解，可将原文句子简化为“our first studies sought to determine whether A might also occur after...”，如此一来，我们便可以很容易知道A所代替的内容即为此次研究之前已经知道的信息，所以本题的答案就是A所代替的内容，即“increase in serotonin observed in rats given a large injection of the amino acid tryptophan”，那么就不难选出选项E“小白鼠被注射大量氨基酸色氨酸之后血清素上升”。

选项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，错在“喂食”，应该是“注射”。

其他选项意思分别为：

A.它们最终需要设计实验，给小白鼠喂食高浓度的蛋白质。

B.血液中色氨酸水平很难被精确地监控。

D.有很多神经递质的产生取决于身体其他地方的新陈代谢过程。