whether a teacher may teach without combining English with mother tongue

I think the teaching of English in the English language is not fully effective because different students' abilities. but different from the school are required to use English RSBI full because of academic demands.whereas if you use a full english to hone students' ability to better know and have a high curiosity. but in practice it is difficult to enforce.therefore, in the field of English language learning is still not fully use the English language to the fullest.