Use when, before or after, the past perfect and the past

Use when, before or after, the past perfect and the past simple to join the sentences, as in the example. 1 The scientist мейд an announcement. He completed his research. amp;gt; When the scientist (had) completed his research, he мейд an announcement./The scientist мейд an announcement after he had completed his research. 2 She got a degree in Engineering. She studied for four years. 3 He worked as a sales assistant. He got a new job as a car salesman. 4 Ann and David were engaged for five months. They got married. 5 Mr. Harris was sick for many weeks. He went to hospital.