1. On one occasion Humboldt took a louse from a servant´s hair and put it under the microscope.
    一次，洪堡从一个仆人的头上拿下一只虱子放到了显微镜的下面。

2. On one occasion a fight broke out at a beach party, with everyone punching and shoving.
    记得在一个沙滩聚会上，发生了一场殴斗，人人都挥拳上阵，相互推撞。

3. On one weird occasion in 1881, the cargo steamer Ellen Austin discovered a small sailing ship, sails waving uselessly in the wind.
    1881年一个诡异的日子里，货轮"艾伦·奥斯丁"号发现了一艘小帆船，帆在风中无望地飘动。

4. On one occasion, when Cavalli-Sforza was taking blood samples from children in a rural region of Africa, he was confronted by an angry farmer waving an axe.
    有一次在非洲乡下，正当卡瓦里-斯福尔扎要从儿童身上采血时，一个愤怒的农人手执斧头出现在他面前。

5. Let´s sing some songs to celebrate this joyful occasion.
    让我们唱几支歌来庆祝这个令人欢乐的节日。

6. It was a mournful occasion.
    这是个悲惨的场面。

7. I´ll speak to him on the first occasion.
    一有机会，我就告诉他。

8. It is possible that upon such an occasion a battle ensued,
    双方可能随之发生搏斗，

9. I am used to travelling by air and only on one occasion have I ever felt frightened.
    我习惯了乘飞机旅行，只是有一次把我吓坏了。