We went to the circus and saw many amazing things under the big top.
The picnic was held under the big oak tree.
The big ship was getting rustie under water.
The sentence "the man with the big smile" is a phrase, specifically a noun phrase. It does not contain a subject and a verb, which are necessary for a clause. Instead, it functions as a descriptive element that identifies a person.
big new pool.
big fish, little pondto be a big fish in a little pond
big fish, little pondto be a big fish in a little pond
A tip is an extra payment for good service, or an extra bit of information that you're sharing to benefit someone. This might be either one depending on the context of the sentence.
"She marveled at the sight of the great big waterfall."
The sentence that shows the correct subject-verb agreement would be "Under the house are two big turtles." To make the first sentence correct it would have to read "Under the house are too big turtles" indicating that the turtles are too large to be under the house.
I was really embarrassed by my big blunder.
He had a big Welt on his face. This may not be a good sentence but it is one
"In". The object of the preposition here is "mouth".