第29题: [单项选择]As intriguing as these results are, much remains unclear about the impact of low doses of a low doses of alcohol ______ system. A. immune B. vulnerable C. chronic D. susceptible 参考答案:A 答案解析:[解析] 语义连贯题。酒精作用的是人的免疫系统,答案选[A]immune“免疫的”。[B]vulnerable“易受伤害的”、[C]chronic“(疾病)慢性的,(人)久病的”和[D]suscept