What are the most common grammatical errors made by non-native English speakers?

I have experience teaching Asian non-native speakers English.

The most common problem are verb tenses and articles. Most asian languages don't have particles such as "a/an" "the" etc and thus tend to either forget or not use them. As far as verb tenses, they tend to often forget the enduring progressive state. i.e. Boy ride bike or Boy riding Bike.

The so much usual mistakes have a tendency to be the ones related to mom tongue have an impact on. In different phrases, a pupil will use both the grammar or the vocabulary in their local language in speakme English in order to result in errors. Take a usual constitution in lots of languages that is noun + adjective. In English it's the wrong way circular, however audio system from France (and plenty of different international locations) would possibly say, "Have you received a pencil blue?"

The most common mistake in general must certainly be not using the third person singular. In other words, saying, for example, "He go to work." or "She have a car."

Among lower level students using the simple present to talk about the past: "I go to the beach yesterday."

Other mistakes vary according to the native language of the student. Speakers of Slavic languages don't use articles, for example, because their languages don't have them.

So far, we're talking about grammar, but for some students (primarily Asians), pronunciation is the biggest problem. For Arabic speakers, spelling and writing are the big problem.

Non-native speakers also have a problem using correct prepositions. In fact many a times during concept checking, I've discovered that they have not understood the meaning of a simple verbal phrase in a text.

My friends teach Koreans ESL . And so far , they're getting troubles in pronunciation , spellings , articles , and verb uses .

Well sometimes the other language they know doesn't use words like an, the, am, etc. Sometimes they forget to say that.