is it possible for english teacher to use english without mother tongue everytime he/ she teach?

In my opinion no, because what? In each class consists of many disciples, and not all students understand what is conveyed by the teacher if the teacher to use English entirely. And teaching and learning activities were less effective. It is also possible to use English teachers alone entirely, but it pertained to the class of superior class, which most likely explanation of all the students familiar with teachers who use English entirely. For instance my class, if teachers use English entirely, not all students understand, and sometimes even to certain things lecturer delivery using the Indonesian language. for what is described is understood by students