例句：
When I came here just now， I saw he was playing with a black and white dog in the garden.
刚才当我进来的时候，我看到他正和一只黑白相间的狗在花园里玩。He是主格形式，所以saw后面跟的是一个进行时态的完整的句子。
see是动词原形，用于一般现在时，或情态动词、助动词后面，作及物动词时意为“看见理解领会觉察拜访”。作不及物动词时意为“看看见领会”。
saw是see的过去式，用于过去时态的句子中。
例句：She screamed when she saw the child fall.当她看见那个孩子跌倒时，她尖声地叫了起来.
All of a sudden he turned about and saw me.他突然转过身来看见了我.
I saw the sudden flare of a flashlight in the darkness.我看到手电筒在黑暗中突然闪出的亮光.
When I entered the room， I saw a man standing at the window.我走进房间时， 看见一个男人站在窗前.
They saw the birds were circling again.他们看见鸟儿又在盘旋.
