A. plays a vital role in selecting people for alternative day and night shifts
B. changes every two hours during the day and every three hours during the night
C. has been used for industries in selecting people for alternative shifts
D. changes after a person has finished the training for alternative shifts
A.To apply for a student loan.
B.To discuss a decision he has to make.
C.To ask for a letter of recommendation.
D.To find out which colleges accepted him.