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

Everywhere man has cut down __________ forests in order to grow crops, or to use __________ wood as fuel or as building material.

A. the; the      B. the; 不填　

C. 不填; the   D. 不填; 不填

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

Everywhere man has cut down __________ forests in order to grow crops, or to use __________ wood as fuel or as building material.

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

The Wilsons live in ______ A-shaped house near the coast. It is ______ 17th century cottage.

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