我写了一篇英语作文My Dream希望那位英语高手能帮忙修改或评价一下。

我帮你重新改一下，里面有很多语法错误。我也帮你加了很多新的用词，听起来比较正规

Scientists have become more and more important to our daily lives, so my dream is to be a scientist in the future. They have invented mobile phones, computers, cars, planes, and so many more things. These inventions make our lives fun and fast. I think I can be a scientist when I grow up. I will invent more inventions that would help to make our lives better. Being a scientist requires a lot of knowledge, so I will study hard and try my best from now on.
I believe I have the ability to become a successful scientist in the future.

纯手打勿复制。我在美国念书5年了放心我的英文，如果你对语法有问题欢迎提问。

Scientists are more and more　important to our lives, so I hope　　　　　to be a scientist in the future.
Now, scientists have invented mobile phones, computers, cars, planes and so on. These inventions make our lives (more fast) faster and more convenient. I think I can become a scientist in the future. When I grow up if I became a scientist I would invent more inventions to change our lives. But
to be a scientist needs rich knowledge. So from now on I must study hard and work hard. I believe that Iam able to become a successful scientist in the future.
还行吧，加油！（间隔开的地方有改动噢）

If you want to write good English, your brain has to think good English. For example, the first sentence or statement needs to be justified by asking a question: why? In writing, nothing is obvious, most has to be justified.