Weird construction: English experts kindly comment

Gaurav 2013-fall wrote:Could an english expert explain the below kind of sentence construction. We dont see such constructions very often. I would use something like ...Tourists at the beach stroill.... and often see children doing........ I have never seen such construction.


Tourists at the beach have often strolled along the sandy shore and saw children playing in the ocean, whose toys lie strewn along the water like shells.

saw children playing in the ocean, whose toys lie

saw children playing in the ocean, whose toys were lying

saw children playing in the ocean, with toys lying

seen children playing in the ocean, with toys lying

seen children playing in the ocean, whose toys have lain


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Gaurav 2013-fall wrote:Thanks Mitch for the answer.

But, my question is more towards the construction of the sentence. I have never seen a construction like this, that is, 'tourists have often strolled on the beach and seen children playing in the ocean'. I dont know why this doesn't sound like a grammatically correct sentence.
Could you explain in what situation we would use such construction.

Thanks in advance!