HyunSeung and Jakkapong,

 

Thank you for posting your thoughtful and accurate summary. This is a version I have written with some changes in sentence structure, different words, etc. You should compare this with your original writing. 

 

Dr. Enzo Emanuele, one of a group of Italian scientists, has found the chemical in the brain called NGF(Nerve Growth Factor). The chemical increased when a person first falls in love. but it fades over a year.

The researchers compared NGF levels of 58 volunteers who were single or in steady relationships. They found that increased levels of NGF make sweaty palms and butterflies in stomachs and perhaps made young men buy red roses and candlelit dinners.

 

In fact, errors were few. The sentences you chose give the most important points in the article. It is nicely done.