1.Centuries ago, ____ man discovered that removing moisture（水分）from food helps to preserve it, and that the easiest way to do this is to expose ______ food to sun and wind.
A. a; the B. the; 不填 C. 不填; the D. the; the
2. I’ve already forgotten ___________ you put the dictionary.
A. that it was where B. where it was that
C. where was it that D. that was it that
3. Male and female students are quite different from each other______ the age at which they begin to develop an intellectual self-discipline.
A. with regard to B. in the light of C. in honor to D. on account of
