第31题: [单项选择]In the author's opinion, ______. A. physiological changes will for sure betray a liar B. the bigger a lie is, the stronger the strain will be C. the degree of the strain depends on the purpose of lying D. a well-trained person can tell lies without being detected 参考答案:A 答案解析:推理题。根据第四段第一句。人类即使在说一个小谎言时,也必然引起一系列的生理反应。