Some of the run-ons are fused sentences (there is no punctuation between the two complete thoughts), and some are comma splices (there is only a comma between the two complete thoughts). One sentence is correct.
1. Slovakia, a country in eastern Europe, was once ruled by the Austro-Hungarian Empire, it is now an independent country.
2. The children in the next car were making faces at other drivers, when I made a face back, they giggled and sank out of sight.
3. Chuck finished reading Mark Twain’s The Adventures of Huckleberry Finn then he began to take notes for his report.
4. The branches of the tree were bare they made a dark feathery pattern against the orange-pink sunset.
5. Ernest Hemingway drove an ambulance in World War I, he based the novel A Farewell to Arms on that experience.
6. Our class wanted to do something for the earthquake victims, we sent a donation to the Red Cross.
7. My ex-husband hit me just once in our marriage, five minutes later I was packed and walking out the door.
8. Charles Lindbergh took off from Roosevelt Field in New York on May 20, 1927 thirty-three-and-a-half hours later, he landed in Paris, France, completing the first nonstop transatlantic flight.
9. The average American teenager spends thirty-eight hours a week on schoolwork. the average Japanese teenager spends about sixty.
10. We stocked our backpacks with high-calorie candy bars, and we also brought bags of dried apricots and peaches.
11. Locate and correct the run-ons in the passage that follows.
My worst experience of the week was going home for lunch, rather than eating at work. My children didn’t know I was coming, they had used most of the bread. All I had to make a sandwich with were two thin, crumpled pieces of...