单选题 It was difficult to see ships in the distance because of the fog .
【正确答案】 B
【答案解析】[解析] 本句意思：迷雾使人难以看清远处的船只。fog雾，烟雾，尘雾。sweat汗；haze雾霾，薄雾；dew露水；frost霜。