One of the keys to the survival of animals is its ability to adapt to changes in the environment. 

A. I never go to the movies if I have work to do

B. I would go to the movies when I had done so much work

C. A lot of work couldn’t prevent me from going to the movies

D. Because I had to do so much work I couldn’t go to the movies

A. frequent 

B. exercise 

C. greater 

D. will have 

A. Wealthy 

B. Impoverished 

C. Privileged 

D. Well-off 

A. palnts and animals 

B. fruits and vegetables 

C. flowers and trees 

D. moutains and forests 

A. They drove fifteen miles off the main road until they had something to eat for the day

B. They neither drove fifteen miles off the main road nor had anything to eat for the day

C. Not only did they drive fifteen miles off the main road, they also had nothing to eat for the day

D. Driving fifteen miles off the main road, they eventually had something to eat for the day

A. The little dog was greatly amused by the way everyone was watching it

B. Everyone felt great and amused when the little dog was watching them

C. The little dog was watching everyone with great amusement

D. Everyone was greatly amused at the little dog they were watching

A. had to be 

B. should have been 

C. had been 

D. must have been