Since it is believed that strong smells can affect the senses，volunteers were required not to eat or drink for eight hours before the experiment.

因为人们认为强烈的气味会影响感觉，所以志愿者们被要求在实验开始前八个小时内不吃不喝。

2．that指代"同类的单数或不可数名词"

One explanation is that women's sense of smell is better developed than that of men，and is linked to recognizing the smell of babies.

-种解释是女性的嗅觉比男性的发达，而且这和识别婴儿的体味有关系。

重点词汇

1．In some cases，different parts of speech (usually a noun and a verb) have the same spelling but different meanings.

在某些情况下，不同的词性(通常是名词和动词)有相同的拼写但不同的含义。

in some cases在某些情况下，有时候

in any case无论如何，总之

in case在......情况下，万一；免得，以防万一

in case of在......的情况下，万一

in this/that case假使这样/那样的话

in no case决不置于句首，引起部分倒装

as is often the case with... 通常就是这样；......是常有的事

(1)Larry told her that he had already put out the fire and she should not move in case she injured her neck.

拉里告诉她他已经把火扑灭，她应该待着不动以防伤着脖子。

(2)Please inform me in advance in case of any change.

万一有什么变化，请提前通知我。

(3)As is often the case with him，he was fined for speeding.

他因超速而被罚款，这对他而言是常有的事。