While he was investigating ways to improve the telescope, Newton made ______ discovery which completely changed ______ man’s understanding of colour.

1. A.
   a; 不填
2. B.
   a; the
3. C.
   不填; the
4. D.
   the; a

While he was investigating ways to improve the telescope, Newton made ______ discovery which completely changed ______ man’s understanding of colour.

A. a; 不填 B. a; the　　C. 不填; the D. the; a

While he was investigating ways to improve the telescope Newton made _______discovery which completely changed ____ man’s understanding of color.

a ,/     B. a ,the     C. /, the     D. the ,a

While he was investigating ways to improve the telescope, Newton made ______ discovery which completely changed ______ man’s understanding of colour.

A. a; 不填 B. a; the　　C. 不填; the D. the; a

While he was investigating ways to improve the telescope Newton made _______discovery which completely changed ____ man’s understanding of color.

a ,/     B. a ,the     C. /, the     D. the ,a