Find a mistake in the four underlined parts of each sentences and correct it

Find a mistake in the four underlined parts of each sentences and correct it
1. My sister had worked in the bank for five years before she had been sent to Da Nang
2. Tom said that he has been very excited to visit Hanoi for the first time in 2005
3. The country has significant changed since we came here in 2007
4. All of us are astonished that life in the countryside to improve a lot
5. By the time she left the shop, she spent all of her money on clothes