单选题 Doctors warned sun-starved tourists who received too much sunlight that they were at serious risk than others of contracting skin cancer.
【正确答案】 C
【答案解析】[解析] 本题考查比较级和固定用法。由连词than可知,前面的形容词应用比较级;at risk为固定用法,意思是“处于……危险中”。所以,答案为C。