I am trying to learn/improve my English by remembering grammar rules. Every day, I read a lot of technical documentation and have many conversations with my colleagues from US.
I already have many phrase templates, but sometimes I urge myself to stop using this and try to figure out the rules by which a phrase was constructed.
So, how common is the usage of the sentence "I'm not understand". (Understand — is a verb in 1st form used after form of be.)
What rules were used? Why doesn't it sound like "I don't understand" or "I'm not understanding"?