Peanut allergies (过敏) are among the most common and most dangerous of food allergies. A tiny exposure to peanuts can mean big trouble for a person with a peanut allergy—not just sneezing or coughing，but something as potentially deadly as narrowing of the airways.
But a recent study suggests that some children may be able to beat back their allergic reactions to peanuts by gradually introducing trace amounts of the nut into their diets. It's too early to say for certain，so if you have a peanut allergy，do not try this at home. But the first results look promising.
Two teams of scientists have been experimenting on a group“of 29 children who are allergic to peanuts”At the beginning of the study，each kid received less than 1/1，000 of a peanut per day. (Imagine splitting a peanut into 1，000 parts!) Over the course of the study， the children gradually increased the amount of the peanut in their diets
Nine of the children have been receiving the treatment for two years，and five of those nine now appear to be free of their peanut allergies，and can eat peanuts with no problem. But the other four have not benefited so much from the therapy（治疗）.
The two teams of scientists are now doing a follow-up study on two groups of children with the allergy. Children in one group will receive the new therapy，while the others will not. Researchers hope this study will help them learn if the therapy truly does work.
Scientists don't understand why some people get peanut allergies and others don't，but are trying to find a way to help people with the allergy. Because of the severity of some peanut allergies，scientists want to know the answer as soon as possible. “This is very encouraging， but remember，it's not something you try at home，”says one of the researchers.
68.According to the passage，the peanut allergy     .
A. can be deadly if only a small amount is used
B. causes a lot of trouble for many parents
C. allows people to eat only small amounts of peanuts
D. is considered the least common and dangerous food allergy
69.Scientists are trying to treat peanut allergies by     .
A. exposing children with the allergy to as many peanuts as possible
B. changing the eating habits of children with peanut allergies gradually
C. giving children Peanuts in slowly increasing amounts
D. exploring ways to resist the feelings caused by peanut allergies
70.The experiment shows that     . 
A. people with peanut allergies can't use small amounts of peanuts in their diets.
B. children are more easily cured than adults
C. all children can be cured of their peanut allergies if given more time of treatment
D. about 55-percent children with peanut allergies have been cured
71. Scientists are now doing a follow-up study in order to     .
A. explore why some people get the illness while others don’t
B. show whether peanut allergies can really be dangerous
C. check whether the therapy really works or not
D. explore whether the allergy can be cured without treatment