I know it's difficult to do that.know about怎么用

I know it's difficult to do that.know about怎么用
I know it's difficult to do that.
know about怎么用

I know it's difficult to do that.know about怎么用
I know it's difficult to do that.对吗
正确
know about怎么用
know about 知道（听说的那种）.
know about 译为“了解”,“知道……情况”.
如：...There's one thing I'd like to know about．有一件事我想了解一下.
I know you
我认识你
I know about you
我听说过你（但我还没机会当面认识你,还不了解你.）