Is the sentence correct or does it contain a coordination or subordination problem? Read the article Controlling Emphasis: Coordination and Subordination to help you out.

1. Old Mr. Langdon is known to his friends as Ace, and he has been playing poker for many decades and does not think that anyone might play better than he can, or at least he would never admit to it.a) is correctb) has a problem
2. While the coach believed that his players were not ready for the tournament, he decided the team should withdraw.a) is correctb) has a problem
3. Melissa used to be a sweet little girl, but ever since she turned 13, she has become moody and irritable.a) is correctb) has a problem
4. Richard, usually a rational man of science, believes that fate plays a stronger part in his life’s course than hard work or planning.a) is correctb) has a problem
5. The local sawmill, which burned to the ground yesterday in the most devastating fire the region has seen in over a century, produced cedar shakes and shingles.a) is correctb) has a problem
6. A federal court judge will examine the draft warrant and accompanying affidavit, and this will lead to a determination of whether there are reasonable grounds for a warrant, and if there are, the warrant will be issued.a) is correctb) has a problem