One of the common comments that authors get after submission is “needs proofreading”. It is one of the convenient ways the reviewer rejects a paper. Because it is one of the first things a reader pay attention to. A paper should be fluent and coherent to the readers, besides its academic values.

On the other hand, there are many authors and researchers whose native language is not English. They may use English as their second or foreign language. So it is not unusual to have some errors in their writings. Even if you are so good at English, a native speaker may understand the paper is written by a non-native. But you can try to reduce the errors by adhering to the rules.

How can I improve my paper in terms of grammar?

In order to write a more comprehensive paper which is containing less grammatical mistakes, you can follow the below items:

• Only use the sentences that are used by native speakers, or take the main structure of sentences from them and substitute words and phrases. To do so, use books and papers written by native authors.
• Use phrases that native speakers employ in their writings.
• Do not forget to use dictionaries. There are different kinds of dictionaries, one for finding parallel words, one for specialized vocabulary, etc.
• Employ prepositions, adjectives, and verbs that are suitable for the other words applied in the sentence.
• Avoid using lots of jargons. Editors prefer easy to understand papers to publish.
• When the writing work is finished, leave it for some days and then review it once again. Also, ask someone for proofreading. Make use of apps and software like “Grammarly” to find grammatical mistakes, as well. In this way, your paper is reviewed by three different people before submission.

What to do if there really is no error in terms of language usage and grammar?

If you have revised the paper and you are sure of the accuracy of what you have written, you can write to the editor and ask her for some clues. Explain that the paper was reviewed by a friend of yours who is a native speaker (or you have hired a native speaker to proofread your work) and no error was found, then ask her to give you some examples so that you can understand where the problem is.

You can read more in “common reasons for paper rejection“.