When I passed the school, I saw her dancing. 當我走過學校時,看見她正在跳舞。
When I passed the school, I found [learned] she was about to dance. 當我走過學校時,看見他正要跳舞。
When I got to the airport, I found [learned] the plane was about to take off. 當我們到達機場時,看到飛機正要起飛。
When I got to the airport, I found [learned] the plane had taken off. 當我們到達機場時,看到飛機已經起飛了。
When I got to the airport, I saw the plane taking off. 當我們到達機場時,看到飛機正在起飛。