Q: How can I improve the usage of "the" in my manuscript?
The editor of my manuscript has asked me to improve my English. Specifically, he/she mentioned that I had misused the word "the." In some places, "the" was not used or was used wrongly.
Writing a scientific paper in English can be a difficult task for non-native speakers of English. It is good that the Editor has pointed this out, so that you can focus on improving your English grammar and writing skills. However, this will take time and a considerable amount of practice. For the purposes of the current manuscript, it will be better if you take the help of an English-speaking friend or colleague in proofreading the paper. You can also use the services of a professional language editing company. Editage also has such a service: https://www.editage.com/editing-services/manuscript-editing.html.
Meanwhile, you can start reading up online about the usage of the definite article or "the" in English in general and scientific writing in particular. You will find a lot of material, including video lectures and practice exercises. If you start learning and practicing grammar on a regular basis, you will definitely start seeing some improvement in your writing in a few months' time.
Here are a few links that I found online explaining the usage of the definite article:
You can also take a look at this fun video that teaches definite article usage through a song.