题目

I had been a happy girl until one day when I was fifteen months old. One of my eyes was badly hurt in an accident. I lost the sight of the eye, with an ugly scar  around it. Children refused to play games with me. It made me very sad. I always walked, loo¬king at the floor, so that people would not see the ugly face. My mother encouraged me to be brave. She told me, Alice, hold your head up high and face the world. If you do, it will be OK, and people will see your beautiful soul . Mom's words meant different things to me over the years. As a little child ， I thought Mom meant （2012?浦东新区二模）下列关于放射性元素半衰期的说法中，正确的是（　　）A．压强增大，半衰期变短B．同种放射性元素在化合物中的半衰期比单质中长C． 22286Rn的半衰期为3.8天，4g 22286Rn经过7.6天就只剩1gD． 3015P的半衰期为14天，若有4个 3015P原子核，经过28天就只剩1个