1. But the cause of malaria remained unknown to 17th-century medicine, and so there was investigation by experiment.
    但对于17世纪的医学来说，疟疾的起因仍属未知，所以便通过实验来进行调查。

2. The tiny painting proved to be an unknown masterpiece by Correggio and was worth hundreds of thousands of pounds.
    那幅不大的画原来是柯勒乔的一幅未被发现的杰作，价值几十万英镑。

3. They can go to a sperm bank and take a chance on unknown genes.
    他们可以去精子库，尝试不知名的基因；

4. Their language is of unknown origin and cannot be placed within any standard classification.
    他们的语言起源不明，也无法根据任何通常分类来归类。

5. Now more than sixty years old, Barbara — who declines interviews but is said to have loved the doll - may be the most famous unknown figure on the planet.
    如今芭芭拉已有60多岁了，她拒绝接受采访，但据说非常喜欢芭比。她可能是当今世上真名实姓不为人知的最著名的人物。

6. He was a man quite unknown about town.
    他在镇上鲜为人知。

7. He crossed the ocean and discovered strange lands, inhabited by a people unknown to Europeans.
    他横渡大西洋，发现了一块奇怪的陆地，那里居住着欧洲人不知道的一个民族,

8. Some iron is lost in sweat, and, for unknown reasons, intense endurance exercise is sometimes associated with bleeding of the digestive system.
    有些铁离子随汗液流失。另外，由于某些未知的原因，高强度的耐力运动有时是与消化系统内出血联系在一起的。

9. Some unknown interval of time passes before her eyes open again, only this time there is no response in them, just a blank stare.
    不知过了多长时间，她又睁开了双眼，只是这一次目光里没有任何反应，只有空空的凝视。

10. Gifts poured in not only from unknown people, but from baby food and soap manufacturers who wished to advertise their products.
    不但素昧平生的人寄来了大量的礼物，而且婴儿食品、婴儿肥皂制造厂商为了替自己产品做广告也寄来了大量的礼物。