第13题: [单项选择]______ human behavior may be caused by eating substances that upset the delicate chemical balance in the brain. A. Deliberate B. Consistent C. Primitive D. Abnormal 参考答案:D 答案解析:[解析] 根据题干可判断,填空处应与upset the delicate chemical balance“破坏微妙的化学平衡”形成语义场共现。[D]Abnormal意为“反常的,异常的”,与破坏化学