I used to travel by air a great deal of when I was a boy. My parents used to live in South America and I used to fly there from Europe in the holidays. An airhostess would take charge of me and I never had an unpleasant experience. I am used to traveling (习惯于某事)by air and only on one occasion have I ever felt frightened. After taking off, we were flying low over the city and slowly gaining height（逐步升高）, when the plane suddenly turned round and flew back to the airport. While we were waiting to land, an air-hostess told us to keep calm and to get off the plane quietly as soon as it had touched down. Everybody on board was worried and we were curious to find out what had happened. Later we learned that there was a very important person on board. The police had been told （被告诉，得知）that a bomb had been planted on the plane. After we had landed, the plane was searched thoroughly（被彻底搜查）. Fortunately, nothing was found and five hours later we were able to take off again.
The writer used to fly much when he was a boy.
The writer’s parents used to live in South Africa.
While they were waiting to land, an air-hostess told them not to be calm.
Nothing was found and nine hours later they could take off again.
There was really a bomb on the plane.