Run-on sentences are common within the writing of people whose first language is not English and in casual sentences of native speakers of the language. A run-on is a sentence with multiple independent clauses or sentences that are not joined or separated properly
Writers whose first language is not English tend to omit commas in places that need commas. This is the most common type of punctuation errors among non-native English speakers.
The subject-verb agreement rule requires a noun to match the plurality of the verb that goes with it. Even native English speakers get wrong time to time, especially if the subject and the verb are not right next to each other.
Idiomatic phrases are learned through experience and exposure to the English language, so it’s difficult for non-native speakers of English to know these phrases right off the bat.
Another part of grammar that gives non-native speakers trouble is countable and uncountable nouns. English would be straightforward if every noun could be pluralized by simply adding an -s or -es at the end, but unfortunately, English is not that simple.
There are three tenses: past, present, and future. But it gets a bit complicated with tenses like past perfect, present perfect infinitives, future perfect, and more.
The importance of capitalization is often overlooked by non-native speakers. These are the main places capitalization errors happen: titles, proper nouns and common nouns, the beginning of a sentences and comma splices
Mistakes with prepositions are up there as one of the most common errors non-native English speakers make. Similar to articles, these English learners will either use the wrong preposition, omit a needed preposition, or put a preposition where it’s not needed.
