экзамен через два часа!! ! помогите пожалуйста. проверьте английский

1. recent poll (reveals, has been revealing) that more than 80 percent of people (believe, will be believing) kissing spreads colds.-- has been revealing, believe
2. Fortunately, this belief (proves, has been proven) false. - has been proven
3. Doctors at a large New York medical center recently (have conducted, are conducting) research concerning the common cold. -have conducted
4. The interviewed hundreds of people who (had been catching, had caught) a cold during the previous year. - had been catching
5. the researchers concluded that cold viruses are most likely to be communicated when a person (has, will have had) hand contact with someone who is sick. - has
6. people who conscientiously (wash, are washing) their hands significantly (reduce, are reducing) the danger of catching a cold. -wash, are reducing
7. Through various tests and observations, doctors (discover, are discovering) that exposure to cold weather (does, did) not make a person (catch, have been catching) a cold. discover, does, catch
8. during the past decade, the American economy (loses, has lost) more than five million dollars per year from lost wages and medical expenses due to common cold. has lost
9. Unfortunately, no cure ( has been discovered, is being discovered) for this persistent illness. has been discovered
10. Be the time a miracle drug (has been found, was being found) millions of Americans (are spending, will have spent) millions of dollars in trying to relieve their miseries. --was being found,are spending

в некоторых случаях возможны два варианта - где и почему?