a sea of people的用法和样例：
- The market is like a sea of people.
- The square was a sea of people and a hubbub of voices bubbled up.
- On National Day, Tiananmen Square was a sea of people.
- I peep out the porthole and see a sea of clouds.
- Life is, at best, a sea of trouble.
- A full busload of people instantly disappeared into a sea of stores.