As corrected, I prefer 1.1.Your first two explanations are the same as those in our textbook.
2.Your previous two explanations are the same as the ones in our textbook.
3.The first two explanations you gave are the same as those in our textbook.
4.The two previous explanations you've mentioned are the same as those shown in our textbook.
I think the third one may be better and the second is not grammatical.
Meanwhile,should I use 'first two explanations','previous two explanations','two previous explanations' or 'fomer two explanations'? And what's the oppsite phrase?
Student or Learner