3. Identify the simple sentence.

In 1970, my mother graduated from Point Pleasant Boro High School.

The gymnast swung around the bar, and the coach stepped on the mat.

The tornado bypassed the town, but the townspeople remained in their shelters.

The factory closed its doors, and more than 200 people lost their jobs.

http://www2.ivcc.edu/rambo/eng1001/sentences.htm

http://www.eslbee.com/sentences.htm

A simple sentence is a sentence that consists of only one independent clause. An independent clause is a group of words that contains a subject and a predicate and expresses a complete thought.

Let's examine each of the sentences given to identify the simple sentence.

1. "In 1970, my mother graduated from Point Pleasant Boro High School."
This sentence contains only one independent clause, "my mother graduated from Point Pleasant Boro High School," expressing a complete thought. Therefore, it is a simple sentence.

2. "The gymnast swung around the bar, and the coach stepped on the mat."
This sentence contains two independent clauses, "The gymnast swung around the bar" and "the coach stepped on the mat," joined by the coordinating conjunction "and." Since it has more than one independent clause, it is not a simple sentence.

3. "The tornado bypassed the town, but the townspeople remained in their shelters."
Like the previous sentence, this sentence also contains two independent clauses, "The tornado bypassed the town" and "the townspeople remained in their shelters," joined by the coordinating conjunction "but." Therefore, it is not a simple sentence.

4. "The factory closed its doors, and more than 200 people lost their jobs."
Similar to the second and third sentences, this sentence also contains two independent clauses, "The factory closed its doors" and "more than 200 people lost their jobs," joined by the coordinating conjunction "and." Hence, it is not a simple sentence either.

Based on the analysis, the simple sentence is: "In 1970, my mother graduated from Point Pleasant Boro High School."