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/.
Word order is of a great importance in Vietnamese language. It is a non-inflecting language and it relies on word order and function words to signal function meaning. The verb “to be” is hardly ever used because Vietnamese adjectives contain their own verbs.
The passive voice is rarely used in Vietnamese language. As I know, the passive voice in Vietnamese is rarer than in most European languages. Use of passive voice in Vietnamese is rare not because Vietnamese speakers avoid the use of passive form nor because teachers teach them that it is not desirable but it seems to be a natural characteristic of Vietnamese expression.
Verb tenses used in English language are extremely difficult to be comprehended by Vietnamese learners. That is because Vietnamese language employs aspect rather than tense. It is possible to express time very precisely in Vietnamese (when that is necessary), although the language doesn’t use complex structure of tenses like other languages (such as English or many other western tongues).
The biggest difficulty of Vietnamese learners of English in learning English is expressing stress by tone. In Vietnamese, each syllable is pronounced with its characteristic tonal pattern. Without its tone, the syllable is not recognizable.
Comparing English with Vietnamese, Vietnamese is much simpler than English when it comes to questions. Most of the questions in Vietnamese expect a yes/no answer.
Example:
(lit. Person – this – have – old – or – not)
Is this person old?
The system of personal pronouns in Vietnamese language is a very complex one. There is not a set of general personal pronouns in Vietnamese like it is in English (I, you, he, she, we, they). The personal pronouns in English can be used freely without external non-linguistic connotations. I can say that every time my students use personal pronouns (especially “he” and “she” and also “my” and “your”) they make mistakes. I always have to say “It is about your father, your father is a man, why are you using ‘she’?”.
Using “it” as a subject is another problem that Vietnamese learners have to face. Impersonal “it” is very often used in English (example: It is raining, it is necessary etc). There is no equivalent of impersonal “it” in Vietnamese.
The English definite and indefinite articles (the, a, an) don’t have exact parallels in Vietnamese language. Instead of articles, Vietnamese language uses a type of word called classifier to make similar distinctions in nouns.
Vietnamese learners of English have some problems using adverbial expressions correctly. A short comparison between how these adverbial expressions are used in Vietnamese and English can be seen below.