With the development of science, human life has changed tremendously. People living in the 18th or 19th centuries would never imagine the advanced household appliances we are now able to enjoy. Every aspect of our lives, for instance, in the field of medicine or agriculture has witnessed great improvements through the application of science.

However, many people complained that science has also brought disasters to human life. Some evil scientists have used their knowledge to do some illegal things. They may use science for the creation of weapons to destroy thousands of lives in wars. They might also use their knowledge to produce drugs to make a lot of money for themselves.

Generally speaking, science has provided us with many valuable things. But if used wrongly, it can also lead to harm. We should try to keep science under control and put it to the best use of mankind.

随着科学的发展，人类的生活发生了巨大的变化。18世纪和19世纪的人无法想象我们现在所享用的家用器具。我们生活的各个方面，比如医药、农业，都经历了科学所带来的改善。

然而，也有人抱怨科学带给人类许多灾难。有些邪恶的科学家利用他们的知识做一些非法之事。他们用科学知识制造武器在战争中摧毁成千上百的生命；他们用其知识制造毒品赚取钱财。

总的来说，科学为我们带来许多有价值的东西。但是一旦被错误地使用，它也能导致伤害。我们应该使之置于我们控制之下，使其为人类发挥出最大作用。

NOTES
1. household appliances 家用设备
来举几个例子：washing machine 洗衣机，vacuum cleaner 吸尘器，microwave 微波炉
2. witness 做动词时有“目睹，见证，经历”的意思。
witness an accident, a murder, a quarrel 目击一起事故、谋杀事件、一场争吵
We were witnessing the most important scientific development of the century. 我们亲眼见证本世纪最重要的科学进展.