Sentence1: Cathy needed to get some blood drawn for the lab. Sentence2: However, Cathy's nurse had trouble locating her vein. Sentence3: Cathy's nurse tried everything, until she finally gave up. Sentence4: Cathy's nurse decided to call her doctor to try. Sentence5: Luckily, Cathy's doctor was able to locate a vein and get the blood.
Cathy, Cathy's nurse, Cathy's doctor