A. their innocence and lack of ilfe experience
B. their raging hormones and lack of life experience
C. their radical attitudes towards life
D. the generation gap between teenagers and their parents
37. Form the passage we can learn that __________ .
A. the teenage brain is a kind of work in progress
B. the new brain scans support the conventional thought
C. the brain’s frontal cortex becomes bigger during the teenager years
D. at the age of 11 or 12 teenagers are unable to find out people’s true feelings
38. The latest study is very helpful in that __________.
A. it can take clearer pictures of teenagers’brains
B. scientists will meet with fewer dangers in their research work
C. it may help scientists understand better the mental illness in teenagers
D. it may enable teenagers to experience fewer dangers during teenager years
39. According to paragraph five, which of the following statements reflects the present medical reality?
A. It is biologically bad for teenagers to play games or lie on the couch watching MTV.
B. Teenager boys should drink six or eight glasses of hot water in the morning everyday.
C. Scientists should apply the findings of brain scans to practical use as soon as possible.
D. Scientists still don’t know how to explain the subtle changes seen in teenager brain scans.
40. The author’s attitude towards the findings of teenagers’ brain scans can be concluded as _________ .
A. cautious
B. positive
C. prejudiced
D. neutral
Passage Three
Scraps of food could soon be helping power your home, thanks to an ultra-cheap bacteria-driven battery. Its developers hope that instead of feeding the dog or making garden compost (混合肥料), organic household waste could top up your home’s electricity.