It’s thought that the accident was caused by human error.
The accident is..............................................................
A.
B.
C.
D.

For the first few minutes she was leading the race, then she began to fall _______.  
A.out     
B.through        
C.back       
D.off

People said that he would ________ a bad end. They were right. He went to prison and died there.
A.come to  
B.come through   
C.come into
D.come round

In an  ordinary optical microscrope, a electric bulb or sunlight is used as light for the stage
A.an
B.ordinary
C.a
D.light

Paul Dunbar wrote poetry in standard English about tradition poetic subjects and about the heroes of  black Americans.
A.standard        
B.tradition     
C. the     
D.heroes

Musical comedies, as an American form of entertainment, often take its subjects from  America’s present or past
A.as   
B. entertainment    
C.its    
D.or

After the Ice Age many species of animals died out.
A.froze                   
B. receded
C.became extinct
D.became extinguished

The gravitational forces of the sun and the moon are fundamental in causing ocean tides. 
A. unique   
B.essential      
C.odd            
D.current

Hypertension is one of the most widespread and potentially dangerous diseases.
A.stretched    
B.popular  
C.common   
D.scattered

Many California mining towns prospered until the gold ran out and prospectors moved on to new areas, leaving boom towns to become ghost towns.
A. declined
B. assembled
C.employed  
D.thrived