Main Verb

1. Economics __________ is known as an inexact science because it relies heavily on variables and subjective judgements.
   
   1. is what
   2. it
   3. which
   4. that it
   Answer: A
   
   
   
2. Not all currencies that are brokered on the world’s major stock exchanges _______ enough to generate windfall profits for the everyday investor.
   
   
   1. valued
   2. to be valuable
   3. of value
   4. are valuable
   Answer: D
   
   
   
3. Written mail, which is currently referred to as “snailmail” by frequent computer users, _______ by email and other electronic technologies.
   
   1. is being slowly transformed
   2. will have been slowly transformed
   3. slowly transforms
   4. was slowly transformed
   Answer: A
   
   
   
4. Among American football aficionados, the tackling of the quarterback behind the line of scrimmage _______ known as a “sack.”
   
   1. is what is
   2. what is
   3. has what
   4. that is
   Answer: A
   
   
   
5. Airport x-ray devices _______ designed more carefully in order to detect the more sophisticated forms of explosive materials that are now produced.
   
   1. must have been
   2. must
   3. must be
   4. must have been being
   Answer: C
   
   
   
6. Emerging in the spring or summer as an elongate, brownish to black beetle, the grub with its velvety body __________ in length from 9 to 10 mm.
   
   1. which has ranged
   2. it will have ranged
   3. ranges
   4. range
   Answer: C
   
   
   
7. In Europe, a definite system of locating the annual cuttings __________ in the management of communal and government forests because under this system the forests can be so organized that an approximately equal yield is secured each year.
   
   1. is extensively used
   2. extensively uses
   3. has extensively used
   4. will have extensively used
   Answer: A
   
   
   
8. The total of livestock of all kinds which used the National Agricultural System in 1910 under pay permits __________ 2.75% in comparison with the previous year.
   
   1. laid off
   2. fired off
   3. fell off
   4. carried off
   Answer: C
   
   
   
9. __________ in his grand operas, Rinsky-Korsakov six times dealt with fantastic and but twice with real or historical subjects.
   
   1. Which of that will observe
   2. It will be observed that
   3. When will it be observed
   4. Observing that when
   Answer: B
   
   
   
10. To Darwin we __________ that has made the interrelations of organisms central in modern natural history.
    
    1. have owed the change
    2. owing the change
    3. the change do owe
    4. owe the change
       
       Answers: D