Bill likes tennis very much. I often see him tennis with his friends.Aplay B．to play C．pl

问题补充：

Bill likes tennis very much. I often see him tennis with his friends.

A．play B．to play C．playing

答案：

解析：句意：比尔非常喜欢网球运动。我常常看见他和他的朋友们打网球。see sb. doing sth 是指”看见某人正在做某事”，不是全过程，表示动作正在进行；see sb. do sth 是指”看见某人做过某事”是看着事情的发生全过程， 是看见某人做某事。故选A。