1. Even the boom that happens when the jet breaks the sound barrier went unnoticed.
    也察觉不到飞机冲破声障时发出的隆隆声。

2. Balanced at the edge of a narrow white platform, I am about to jump head first into a hot new phase of Japan's leisure boom: indoor sky diving, without a parachute.
    我在一块窄窄的白色跳板前端站稳，准备头朝下跳出去。这一跳将跳进日本休闲热中的一个崭新的热门项目：室内蹦极跳，不带降落伞的。

3. The economic boom tapered off in the 1970s.
    经济繁荣在七十年代慢慢消失了。

4. There is a leisure boom in Japan, and like many national trends here it is largely a government-led phenomenon.
    日本掀起了休闲热，就像这里的很多全国性潮流一样，这也是在政府倡导下出现的。