题目

On Nov. 18, 1995, Itzhak Perlman, the violinist, came on stage to give a concert at Avery Fisher Hall at Lincoln Center in New York City. If you have ever been to a Perlman concert, you know that getting on stage is no small achievement for him. He was stricken with polio(小儿麻痹症) as a child, and so he has braces(支架) on both legs and walks with the aid of two crutches(双拐). He walks painfully, yet majestically, until he reaches his chair. Then he sits down, slowly, puts his crutches on the floor, undoes the clasps on his legs, tucks one foot back and extends the other foot forwa18．下列实验操作，正确的是（　　）A．在量筒中进行化学反应B．给试管里的固体加热，管口略向下C．用100ml量筒量取2ml的水D．为了节约，用剩的药品放回原瓶