Here I am talking about Vietnamese learners’ problems in studying English, not other problems. Probably, more than any other nation, Vietnamese learners have a very difficult time studying English. Here I will point Vietnamese pronunciation because this is the biggest issue. Vietnamese learners have particular difficulties with some or all of the following sounds: /f/, /θ/, /ð/, /z/, /ʃ/, /ʒ/, /ʧ/, /ʤ/, /p/, /b/, /l/.
The closest Vietnamese equivalent to /f/ is bilabial. Pronouncing the word “fifteen” is a difficult task. They will say “fipteen”. This is a problem not only for students, but for Vietnamese teachers of English as well. Everybody pronounce “fipteen” so, fixing this problem seems to be an impossible task.
Vietnamese learners tend to pronounce final stop (/p/, /t/, /k/) unexploded in all contexts. Not only these sounds, but almost all final sounds are missing from their speech. Words like “like”, “line”, “light”, “lie” are pronounce “lie” /laɪ/.
Initial t is unaspirated in Vietnamese, producing a sound which can be confused with English /d/. However, there is a strongly aspirated initial /th/, written th in Vietnamese, which learners may produce as the equivalent of English th (/θ/, /ð/). I have been criticized many times by the Vietnamese English teachers for my /t/ sound which they say it sounds “too heavy” and I should pronounce it “smoothly” (these are exactly their words).
/g/ sound is frequently pronounced laxly without full closure, which gives it a guttural sound. /g/ sound in “egg” is not pronounced by Vietnamese learners.
Final /s/ is not pronounced when it should be and it is pronounced when it shouldn’t. Pronouncing plural form for a noun seems to be an impossible task.
Using of “to be” is always a big problem. “My name Lam”, this is the way Vietnamese speak. Although they know the rule, they don’t apply it.
Vietnamese language is a mono syllable language which rises to mistakes. Producing multi syllable words is another difficult task. Simple words like “because” and “of course” are pronounced /bicɔ/ and /ɔfcɔ/, the second half of the word is not pronounced.
The word “like” is often pronounced “play” by the beginner learners. I couldn’t figure out why it is pronounced like that.
The –ed used for past tense in the end of the regular verbs is not pronounced. Vietnamese language doesn’t have such a suffix.
Two consonant sounds next to each other (not in initial position) also create big problems in pronunciation. Usually is chosen one of them and the other one is omitted.
Such mistakes persist and are very difficult to eliminate.