a boom in car sales的用法和样例：
- The 1989 collapse of the Berlin Wall led to a boom in car sales in Europe, and in 1992 BMW outsold Mercedes-Benz in Europe for the first time.
- This year has seen a boom in book sales.
- There has been a boom in exports this year.
- There's been a boom in exports this year.
- Record profits in the retail market indicate a boom in the economy.