Is this a proper sentence? It takes courage to obey difficult.

Is this a proper sentence? Most bears hibernate during the cold winter months, so you don't have to worry about seeing them during a winter walk.

Is this a proper sentence? The homesick girl ran to meet her parents, she was so glad they were finally home.

Is this a proper sentence? The little boy. 

Is this a proper sentence? After eight hours of sleep.

Is this a proper sentence? Bob studied diligently for his math test and he passed.

Is this a proper sentence? Adam looked distressed as he saw the work piled before him.

Is this a proper sentence? An invention is the creation of something that never existed before.

Is this a proper sentence? John opened the garage door for his father he was trying to be helpful.

Is this a proper sentence? We play chess when it rains.

Is this a proper sentence? A penny is.

Is this a proper sentence? This has been a wonderful year of new experiences will next year be as good?

Is this a proper sentence? Thomas Edison was perhaps the greatest inventor in history his first invention was a vote recorder.