what are the basic mistakes found in sentence transformation?
Your query is not very clear to us. If you want to ask what kind of changes you are generally asked to make while transforming a sentence, we would like to ask that the examiner can ask you to change the tense or the voice. He may also ask to convert a sentence from direct to indirect speech. Often students are asked to make a sentence with some starting words which should mean the same as original sentence in the question. In case you intended to ask something else, we would request you to elaborate your query so that we may assist you suitably.