Upon entering the thymus, thymocytes are classified as double with regard to coreceptors; before exiting as single-positive, naïve T cells, they pass through a period in which they are double . Question 7 options: positive; negative negative; positive Both "positive; negative" and "negative; positive" are correct. Neither "positive; negative" nor "negative; positive" are correct. Coreceptor expression state does not change in the thymus.