Scientists have spent years_________ into the effects of certain chemicals on the human brain with no results. A: studying B: investigating C: researching D: inspecting

How many years does a decade consist of? A: 15 years B: 10 years C: 8 years D: 100 years

How many years had Rip been asleep?( ) A: twenty years B: ten years C: fifteen years D: thirty years

Those years that have 365 days a year are called_____. A: regular years B: leap years C: Chinese years D: solar years

How many years has the company been operating A: 15 years B: 20 years C: 25 years D: 30 years

‍Junior college in America is _____.‍‍‍ A: five years B: four years C: three years D: two years

A new president in America is elected every______. A: five years B: six years C: four years D: three years

How many years later did the author become Mark’s Math teacher again A: 3 years B: 4 years C: 5 years D: 6 years

MMPI is suitable for people of ( ). A: Over 16 years B: Under 16 years C: 16-60 years D: Over 60 years

How many years passed between her graduation from medical school and the opening of her hospital? ____ A: Eight years B: Ten years C: Nineteen years D: Thirty-six years