Question

some animals never leave
the cave and live in
complete darkness.
is this a simple, compound,
or complex sentence?
since they live in complete
darkness, some cave
dwelling animals are born
without eyes.
is it a fragment, run - on, or
complete sentence?
how can they survive
without?

Explanation:

1. For the first sentence: A simple sentence has one independent clause (a complete thought with a subject and predicate). "Some animals never leave the cave and live in complete darkness" has one subject ("some animals") and a compound predicate ("never leave the cave and live in complete darkness"), forming a single independent clause.
2. For the second sentence: A complex sentence has one independent clause and at least one dependent clause. "Since they live in complete darkness" is a dependent adverbial clause, and "some cave dwelling animals are born without eyes" is the independent clause.
3. For the third sentence: A sentence fragment is an incomplete thought that lacks a necessary component. "How can they survive without?" is missing the object that "without" refers to, so it does not express a complete thought.

Answer:

1. First sentence: Simple sentence
2. Second sentence: Complex sentence
3. Third sentence: Fragment