While I was walking in the field,I saw him running.

sought

leaped

Where was he seen by you? = Where did you see him?

Where they did they go yesterday. 

Where they did they go yesterday.

Where there is smoke, there is fire - There is no smoke without fire

Where have you come from ?

When you think about the job.

When he was four, he left his village (Make it complex). 

= At the age of four, he left his village.

When he began to drink water, a wave swept him away. He was about to drown."

What a nice fellow he is!

A computer is an artificially intelligent machine that is programmed to work under fixed condition; But the human brain is naturally intelligent and it is able to operate on ever changing conditions.

The word knowledge is an abstract noun

"River" is a common noun