水的消毒剂常用氯气（C12）、二氧化氯（ClO2）、漂白粉[有效成份为Ca（ClO）2]等，这三种都含有（ ）
A．氯分子
B．氯元素
C．原子团
D．氯离子
A、三种物质中只有氯气中含有氯分子，故A错误；
B、根据三种物质的化学式可知，三种物质中都存在氯元素，故B正确；
C、根据三种物质的组成，只有漂白粉中有原子团ClO，故C错误；
D、根据三种物质的构成可以看出，都不存在氯离子，故D错误；
故选B．
One afternoon in January in 1998, Susan Sharp, 43, and her 8-year-old son David, were walking across an icy square, when Susan’s cane(手杖) slipped on the ice. Her face 36 first into the mud. David 37 her mother’s side, “Are you all right, Mom” 38 , Susan pulled herself up, “I’m okay, Honey,” she said. Susan was falling more 39 since she had trouble walking. Every inch of ice was a 40 danger for her. “I wish I could do something,” the boy thought. David, too, was having 41 of his own. The boy had a speech problem, so at school he talked 42 . One day, David’s teacher announced a 43 homework. "Each of you is going to come up with an 44 ," she said. This was for "INVENT AMERICA", a national competition to encourage creativity in children. An idea 45 David one evening. If only his mother’s cane didn’t slip on the ice. “What if I 46 your cane to a nail coming out of the bottom” he asked his mother. “ 47 the sharp end would scratch(划破) floors,” Susan said. “No, Mom, I 48 make it like a ball-point pen. You take your hand off the button and the 49 returns back up.” Hours later the cane was finished. David and his father 50 as Susan used it to walk 50 feet about the 51 . Happily Susan cried out, “It 52 !” In July 1999, David was 53 national winner for the "INVENT AMERICA". David began to make public appearance. Thus he was forced to communicate 54 .Today, David is nearly free of his speech problem, and his 55 is becoming well accepted.
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