下列说法正确的是（　　）

    Tai Lihua is a Chinese woman. She is very beautiful. As a child, she became deaf and dumb(哑的). She couldn't hear or say. She was very sad. Later, she had a teacher. The teacher taught her to dance. Though she couldn't hear, she was very hard­working. She danced very well. Now, she is very famous. She is not sad any more.

在高速公路上发生一起交通事故，一辆质量为1500kg向南行驶的长途客车迎面撞上了一辆质量为3000kg向北行驶的卡车，碰后两辆车接在一起，并向南滑行了一段距离后停止．根据测速仪的测定，长途客车在碰前以20m/s的速率行驶，由此可判断卡车碰前的行驶速率（   ）

中国继续坚定不移地奉行独立自主的和平外交政策。下列最能体现独立自主这一立场的是（　　）