题目

患甲状腺肿大（大脖子病）是边远山区常见的地方病，下列元素对该病有治疗作用的是  A．钠元素        B．氯元素        C．碘元素        D．铁元素  答案：C解析:人体缺碘，容易患甲状腺肿大，所以答案是C。 –Mrs Black, could you give me some advice on how to write an application letter?–With pleasure. Remember that the letter should be written in the formal ______.A．value B．styleC．effect D．mood