问题
单项选择题
Doctors warned sun-starved tourists who received too much sunlight that they were at serious risk than others of contracting skin cancer.
A．with more serious
B．at seriously
C．at more serious
D．seriously with
答案
参考答案：C
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。