Giúp mik với mọi người

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1. After he had died, she took up his position at the university.
2. It's three years since we visited our hometown.
3. When the police arrived at the spot, the robbers had got away.
4. Marie was the first woman who received a PhD from the Sorbonne.
5. The founding of the Radium Institute made her dream come true.
6. When he got to the airport, his plane had taken off.