题目

I have eyes that are said to be “cow brown,” and my long fair hair is my best feature （特征）.I’m not overweight, but I’m not too  1  either. I’m relatively happy with my   2  , but where did I get it? Do I share the same features as some unknown stranger?   3  , while walking down the street, I tried to  4  that stranger, imagining that one of the women I passed  5  possibly be my biological mother（生母）. For a long time I wondered what life would be like with  6  . I was never  7  with my life. I just never  8  wondering what it would be like to have be关于摩擦力做功的下列说法不正确的是(　　) A．滑动摩擦力阻碍物体的相对运动，一定做负功 B．静摩擦力起着阻碍物体相对运动趋势的作用，一定不做功 C．静摩擦力和滑动摩擦力一定都做负功 D．系统内两物体间的相互作用的一对摩擦力做功的总和恒等于0