Each year in the United States, many black teenagers _______ of school, either because they cannot keep up or they have to work to support their family.
B
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Attendance at football matches have _____ since the coming of television.
A baby might show fear of an unfamiliar adult, _______ he is likely to smile and reach out to another infant.
Thewealthofacountryshouldbemeasured________thehealthandhappinessofitspeopleaswellasthematerialgoodsitcanproduce.
Wemust______thattheexperimentiscontrolledasrigidlyaspossible.