Pronunciation
Knowing how to pronounce words in English can be very difficult as it isn't always obvious. English speakers have been taught these from an early age, which is how they know not to pronounce the ‘k' on ‘knight' , they are taught the subtleties in how to pronounce something to communicate the right message. Furthermore, depending on the first language of the English student, it can often be difficult to pronounce certain words properly, having not ever had to create that phonetic sound before.