Another reason English is so hard to pronounce correctly is because of its 'syllable structure'. In many languages, especially Asian languages such as Japanese and Chinese, syllables very often go:
Consonant - Vowel - Consonant - Vowel
This means that English words are often said this way.
For example, the word 'hot dog'
consonant vowel consonant consonant vowel consonant
This is shown here, with C standing for consonant and V standing for vowel
Now this can often be said wrong:
Notice how there are now four vowels instead of two.
This often happens with English words that end in a special type of consonant called a 'stop' consonant. 'stop' consonants are sounds like b, d, g, p, t, k and here are some words that end in them:
It is important that you do not put an extra vowel at the end, for example some people will say 'bed' like 'bed a' however this is wrong.
Syllable structure can get quite difficult in English, for example:
'conscientious' has this structure
And 'glimpsed' like before, is like this:
|C C V C C C C|
This has two consonants, then one vowel, then four consonants in a row.