1. Swedish scientist.
2. Yes, he did.
3. He was extremely unhappy.
4. He was 63 years old.
***
1. Mary asked me if Bac Giang was a mountainous province.
2. This machine hasn't been used for ages.
3, Unless you keep your feet dry, you will catch a cold.
4. I haven't spoken to her for 5 years.
Bn học tốt!!