V.
1. The problem of energy shortage will be solved by using solar energy
2. It is interesting to travel around the world
3. I haven't seen Hoa since 2012
4. This building was built 2 years ago
VI
1. Có "next month", chỉ kế hoạch -> are going to visit / are visting là hợp lý nhất
2. Có "two years ago" -> collected
3. Hỏi về kinh nghiệm -> done
4. Có "every day", dạng bị động -> are sent