What is sentence of exist?

It's difficult to give a single sentence that perfectly encapsulates the meaning of "exist," as it's a broad and philosophical concept. Here are a few examples depending on the context:

Simple & Direct:

* The universe exists.

* Life exists on Earth.

* My doubts still exist.

More nuanced:

* The question of whether or not God exists has been debated for centuries.

* Despite the hardships, hope still exists.

* To truly exist is to live with purpose.

Figurative:

* The rumors of his disappearance simply do not exist.

* My fear of failure exists only in my mind.

* The world they lived in exists only in their imagination.

Ultimately, the best sentence to use will depend on the specific context you are discussing.