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We can never expect    bluer sky unless we create     less polluted world.

A. a; a                               B. a; the

C. the; a                             D. the; the

We can never expect____ bluer sky unless we create_____less polluted world.

A. a; a                                   B. a; the

C. the; a                                 D. the; the

We can never expect____ bluer sky unless we create_____less polluted world.

A. a; a                                   B. a; the

C. the; a                                 D. the; the

We can never expect         bluer sky unless we create         less polluted world.

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

We can never expect____bluer sky unless we create____ less polluted world.  

A. a; a                                   B. a; the  

C. the; a                                D. the; the  

We can never expect    bluer sky unless we create     less polluted world.

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

We can never expect    bluer sky unless we create     less polluted world.

     A. a; a                                   B. a; the

     C. the; a                                D. the; the

We can never expect _______ bluer sky unless we create_______less polluted world.

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

We can never expect ________bluer sky unless we create _____less polluted world

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

We can never expect ____ bluer sky unless we create _____less polluted world.

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