"Have you seen the sea?" is the correct way to ask if someone has seen the sea in Engpsh.

The phrase "the sea" refers to a large body of saltwater that is usually surrounded by land. It is often used to describe the ocean, which is the vast body of saltwater that covers the majority of the Earth's surface.

The phrase "have you seen" is a way of asking if someone has experienced or witnessed something. It is often used to inquire about someone's experiences or observations.

Here are some examples of how "have you seen the sea?" might be used in a sentence:

"I've always wanted to go to the beach and see the sea. Have you seen it before?"
"The sea is so beautiful at sunset. Have you had a chance to watch it?"
"I heard that the sea is really rough in the winter. Have you seen it when the waves are high?"

In Chinese, the phrase "你看过海吗" means "have you seen the sea?" It can be translated as "你有看过海吗?" or "你曾经看过海吗?"