The best times to visit Shangri-la are spring and autumn the temperature is at its mildest.
A. when
B. where
C. that
D. which
网友回答
(答案→)A. when
B. where
C. that
D. which
解析：考察从句连词的选择，该句为定语从句，先行词是spring and autumn，在从句中充当时间状语，句意为，参观香格里拉最好的时间就是春天和秋天，那个时候天气最温和。