题目

    You hear this，“No wonder you are fat．All you ever d0 is eat．”You feel sad．“I skip my breakfast and supper．I run every morning and evening．What else can I do?”     Basically you can do nothing．Your genes，not your life habits，determine your weight and your body constantly tries to maintain it．     Albert Stunkard of the University of Pennsylvania found from experiments that“80 percent of the children of two fat parents become fat，as compared with no more than 14．percent of the children of two parents of normal weight．”        How can obes下列实验方案能达到目的的是 [     ]A．除去Fe粉中混有的I2：加热使I2升华 B．除去NaCl固体中混有的MgCl2：加入KOH溶液后过滤，滤液蒸发结晶C．除去碳酸钠中混有的碳酸氢钠：加入过量的氢氧化钠溶液，蒸发结晶 D．除去氢氧化镁中混有的氢氧化钙：放入水中搅拌成浆状后，加入足量氯化镁溶液，加适量水过滤洗涤