Here are the sentences filled in with the correct words:

1. During the rush hours, some parts of Ha Noi and Ho Chi Minh City often packed with people and **vehicles**.
2. When James visited Hoi An last year, I spent most of my time **wandering** around and looking at the ancient temples, houses and bridges.
3. When you visit Hanoi, try some street food there because it is really delicious and **delightful**.
4. I think living in a city has a number of **problems** such as traffic jams, traffic accidents, noise pollution, visual pollution and water pollution.
5. People say that air pollution together with littering is causing many **problems** in our city now.
6. London is one of the largest cities in the world. Its population is a lot smaller than Tokyo but it is by far the most **popular** tourist destination.
7. Formerly known as Saigon, Ho Chi Minh City is a metropolis that is still young but very **dynamic**.
8. Hue becomes one of the most **popular** destinations for travelers to Vietnam with a number of three million tourists a year.
9. Hoi An used to be one of the **busiest** ports of Southeast Asia, which were used by the Japanese, Portuguese, Dutch, French and Chinese merchants.
10. Nha Trang, a **delightful** coastal city in Central Vietnam, is generally recognized as Vietnam's best beach destination.