某无色气体可能含有H2S、SO2、CO2、HI、HCl、NO2气体中的一种或几种，将气体通入过量氯水后，得到无色溶液，向该溶液中滴入BaCl2溶液，有白色沉淀生成，则下列叙述正确的是（ ）
A．该气体中肯定含有SO2
B．该气体中肯定含有H2S和SO2
C．该气体中肯定含有SO2和CO2
D．该气体中肯定含有H2S、CO2和HI
答案：A
NO2 为红棕色气体，排除；通入氯水后，成无色溶液，说明气体中有还原性气体存在，即有H2S或SO2中的一种无HI气体；滴入BaCl2溶液，有白色沉淀生成即气体中有SO2无H2S；CO2存不存在不影响实验现象；
It was a bitter, cold evening in northern Virginia. The old man’s beard was 11 by winter’s frost while he waited for a ride across the river. The wait seemed endless. Then he heard the weak sound of hooves(马蹄) advancing along the frozen path. 12 , he watched as several horsemen rounded the bend. He let the first one pass by, then another. As the last rider drew near where the old man sat, the old man 13 the rider’s eye and said, “Sir, would you mind giving an old man a ride to the other side of the river?” Reining(勒住) his horse, the rider replied, “Sure thing.” Seeing the old man unable to 14 his half-frozen body from the ground, the horseman helped the old man onto the horse and took him to his 15 . On the way, the horseman said: “Sir, I notice that you let several other riders pass by. I'm 16 why, on such a bitter winter night, you would wait and ask the last rider.”The old man looked at the rider and replied, “I know people pretty good. When I 17 the eyes of the other riders, I immediately saw there was no 18 for my situation. But when I looked into yours, kindness and compassion(同情) were obvious. I knew that your gentle spirit would give me help in my time of 19 .”Those heart-warming comments 20 the horseman deeply. “I'm most grateful for what you have said,” he told the old man. “May I never get too busy in my own affairs that I fail to respond to the needs of others with kindness and compassion.”
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