Recently one of my friends told me that there is distinct difference between 'know of something' and 'know about something' expressions. 'know of' is used when you have personal experience with wha. Know 、know about和learn about 的区别know 、know about和learn about 的区别：一，不同的含义1，know的意思是：认识，知道，了解例句：i want to know if you are right.我想要知道你是否正确.
I know (about) this difficulty/problem. In the first sentence, it seems to me that "to know" expresses that the speaker experienced the problem/difficulty before. Feb 23, 2015know in (1) refers to the clause that comes right before it, so there's no pronoun necessary -- it's essentially a transform of i know it's your job.
In (2), however, the object of know is.
'/><text x='50%' y='52%' font-family='Arial,Helvetica,sans-serif' font-size='44' fill='white' text-anchor='middle' dominant-baseline='middle'>Akik</text></svg>)
