Some interesting (4)_____ have been done in libraries. If strangers come too close, many people get up and leave the building; others use different methods such as turning their back on the i

Some interesting (4)_____ have been done in libraries. If strangers come too close, many people get up and leave the building; others use different methods such as turning their back on the intruder. Living in cities has made people develop new skills for dealing with situations where they are very close to strangers. Most people on crowded trains try not to look at strangers; they avoid skin contact, and apologize if hands touch by mistake.