看到 + (了) + Object
The compound verb 看到 (kàndào) means "to see" or "to catch sight of." It combines the verb 看 (to look) with the result complement 到, indicating that the action of looking resulted in actually perceiving something.
我在街上看到你朋友了。
Wǒ zài jiē shàng kàndào nǐ péngyou le.
I saw your friend on the street.
她看到那条消息就哭了。
Tā kàndào nà tiáo xiāoxi jiù kū le.
She cried as soon as she saw that message.
你有没有看到我的钥匙?
Nǐ yǒu méiyǒu kàndào wǒ de yàoshi?
Have you seen my keys?