The old man sat in front of the television every evening, happy _____ anything that happened to be on.

A．to watch

B．watching

C．watched

D．to have watched

在点的曲线运动中，a_t，v，s三者之间的关系与点的直线运动中a，v，s三者之间的关系是否完全相同（）。

A.完全相同

B.不完全相同

C.完全不相同

D.不确定