The over-use of present participles -- Using present participles as if they were verbs. It is hard for students to comprehend that present participles are not verbs, so they use them as if they were verbs. As a result, the participles push real verbs out of the student's vocabulary and the student ends up talking in a verb-free style. This problem is especially obvious among Asian speakers whose native languages do not use verbs. Here is an example from a poem by William Wordsworth. First I'll say it in the poet's words. Then I'll write it in a verb-free style using participles: Good: "My heart leaps up when I behold a rainbow in the sky" Bad verb-free style: "The visibility of a rainbow in the sky gets my heart leaping up"

Starting a sentence with 'so'. It drives me crazy.

Unfortunately, English spelling is very unphonetic and irregular. So, sometimes it can be hard to understand a person if they place the stress on the wrong syllable or otherwise don't pronounce something correctly. Having an accent isn't a problem, but I'm more referring to when people spend a lot of time reading our very unphonetic spellings and then have trouble with pronunciation. Listening while reading subtitles could probably help, then the learner can notice the weirder spelling/pronunciation features of English.